Jump to content

Engine dies when slowing down from highway speeds


huptoy

Recommended Posts

I have a 1931 Hupmobile and a 1953 Willys both die when I slow down from highway speeds of 50 to 60 MPH to 20 or 30 at a ramp. I have corrected the problem by increasing the idle speed but this is a work around and not a fix. Where is my problem, is it in the carb or electrical? The Wllys started this last weekend when we took a 600 mile trip of highway and back road tour. I am looking for suggestions.

Link to comment
Share on other sites

If all you did was increase idle speed then it sounds as if it is related to fuel delivery. Since they are both doing it I would look at the possibility of bad fuel (i.e. old fuel). It would be a strange coincidence if it were electrical or plugs, etc.

OR.....

Is there some maintenance, tinkering, etc. that you have performed on both cars such as rebuilding carbs, etc.?

One other thought. Are you running platinum plugs? Carb cars tend to hate platinum plugs (don't ask me how I know)

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bob Hill</div><div class="ubbcode-body">One other thought. Are you running platinum plugs? Carb cars tend to hate platinum plugs (don't ask me how I know) </div></div>

I would like to know how you know. As long as the ingition system is working properly, there is no valid technical reason for your claim. The method of fuel delivery is irrelevant. I've run both platinum and regular plugs in the 390 in my Galaxie and both work without trouble.

Link to comment
Share on other sites

I ran platinum plugs in my 1975 BMW 2002 (has carb). It ran horribly bad, cut out like his did, wouldn't start if it was hot and was off more than 5 minutes, etc. All this happened right after changing my plugs. One mechnic asked if I was running platinms and I said yes. Immediately changed back to a standard plug and all teh problems went away and it never happened again. Decided to test the theory and bought another brand of platinum plugs and the same thing happened again - changed back and my problems went away so yes they can cause problems.

So whether you "think" there is a valid technical reason or not, my "beta testing" proved that it is a possibility on some cars

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bob Hill</div><div class="ubbcode-body">I ran platinum plugs in my 1975 BMW 2002 (has carb). It ran horribly bad, cut out like his did, wouldn't start if it was hot and was off more than 5 minutes, etc. All this happened right after changing my plugs. One mechnic asked if I was running platinms and I said yes. Immediately changed back to a standard plug and all teh problems went away and it never happened again. Decided to test the theory and bought another brand of platinum plugs and the same thing happened again - changed back and my problems went away so yes they can cause problems.

So whether you "think" there is a valid technical reason or not, my "beta testing" proved that it is a possibility on some cars </div></div>

Once is an anomoly. Twice is a coincidence. Three times is a trend.

I can think of numerous reasons that the platinum plugs did poorly in your car:

1. You were sold the incorrect or incompatible plugs - I am sure you are aware that spark plugs come in different heat ranges and that the engine behavior can vary depending on that heat range. I have found that just because a spark plug is sold as the "equivalent" of the one you normally use, that does not guarantee that the heat range is the same. You will find this difference between different brands pf plugs and different type plugs within a band. Also, there can be physical construction differences between equivalent plugs. I know for a fact that the platinum plugs that came originally in my 98 Ford Expedition are physically different than the ones sold as replacements. The original plugs used a short thread section that screwed into the head. They experienced many problems with improper gasket sealing, poor running, and in the Lightning Pickups that used a supercharged version of my engine, they were being blown out of the plug hole. These problems are all well documented. The replacement plugs use a longer thread section and have no problems at all.

2. Your plugs were faulty or gapped improperly. I have had bad plugs before. Electrodes break off. Bad plugs between two different brands? Less likely, but still possible. Because of the design of the electrodes, platinum plugs may need to be gapped differently. In my experience, they can be gapped slightly wider.

The only real advantage a platinum plug (or iridium) has over a standard plug is service life. They will fire cleaner because they last longer and the electrodes wear less, but they don't fire any hotter or otherwise better. Plugs with multiple ground electrodes will fire cleaner because the spark will always take the path of least resistance which could vary from spark to spark. I have used both platinum and regular Autolite plugs in my 390 and the only difference I have noticed is better plug life in the platinums. It is noticiable in only 5000 miles. There was no real performance advantage with the platinums over standard plugs.

A spark plugs only purpose in life is to fire a fuel/air mix. It does not know if that fuel air mix came from a carb or fuel injection. As long as the mix is within proper bounds, it will fire. If anything, the reason a platinum plug may fire a poor mixture more easily than a standard plug after many miles is again due to the cleaner spark available because of less wear on the electrodes. As long as the ignition system is working properly, it doesn't matter if the plug is platinum or copper. It doesn't take any more energy to fire one or the other.

As far as to why your car reacted so poorly to platinum plugs, I have no idea. But if all you did was swap plugs with no other investigation, then I suggest that you don't know either ("Doctor, it hurts when I do this." "Well, don't do it then."). I will say that I seriously doubt it was because you simply ran platinum plugs in a carbureted car.

Link to comment
Share on other sites

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bill_Haegele</div><div class="ubbcode-body">

As far as to why your car reacted so poorly to platinum plugs, I have no idea. But if all you did was swap plugs with no other investigation, then I suggest that you don't know either ("Doctor, it hurts when I do this." "Well, don't do it then."). I will say that I seriously doubt it was because you simply ran platinum plugs in a carbureted car. </div></div>

I am a pretty decent mechanic and certainly know how to select plugs and how to gap plugs. Suggest you do some research on the internet and you will see that this isn't that uncommon of a problem, especially on 4 cylinder and 6 cylinder cars.

Maybe the real problem was that I let someone touch it at a car show smirk.gif

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bob Hill</div><div class="ubbcode-body">Maybe the real problem was that I let someone touch it at a car show smirk.gif </div></div>

Man, I try to have a civil technical discussion, understand your problem, and offer a possible explanation and what do I get? Smart ass comments that have nothing to do with the topic at hand. Pretty pathetic. If your troubleshooting techniques consist of throwing parts at something until you get it to work, you are not much of a mechanic. I'm certainly glad your not my mechanic.

Link to comment
Share on other sites

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bill_Haegele</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bob Hill</div><div class="ubbcode-body">Maybe the real problem was that I let someone touch it at a car show smirk.gif </div></div>

Man, I try to have a civil technical discussion, understand your problem, and offer a possible explanation and what do I get? Smart ass comments that have nothing to do with the topic at hand. Pretty pathetic. If your troubleshooting techniques consist of throwing parts at something until you get it to work, you are not much of a mechanic. I'm certainly glad your not my mechanic. </div></div>

I couldn't be - I would have to touch your car : )

Obviously I am a pretty good mechanic and a pretty good restorer of cars since I have two Senior Cars to show for my efforts (and yes I did the restoration work) so I am not too concerned about trying to prove myself to you.

Let's just call it a day and forget it

Link to comment
Share on other sites

Guest simplyconnected

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: huptoy</div><div class="ubbcode-body">Where is my problem, is it in the carb or electrical? </div></div> I assume your gas is fresh. Lower voltage spark will cause poor/no combustion. I don't know how both cars would act up at the same time, but I once had a car that burned out both headlights at the same time. I swore it was impossible.

Check your coils and spark plugs on both vehicles. When you are decellerating, your vaccuum is at its highest, air/fuel at its leanest. Makes sense to kick up the idle screw a little.

The battle between platinum/copper spark plugs is VERY interresting. I've wondered about this myself. My EFI engine had a hesitation; sort of a 'dead' spot that went away once I went back to conventional plugs.

Now I find, other clubs telling folks to NOT use platinum for turbo engines. Harley's use the spark plug resistance for 'anti-knock'. Installing platinum negates the anti-knock because of higher resistance. One site claims their cars work best on copper plugs:

DSMTUNERS.COM

"Here's the answer to one of those common questions: "My car stumbles/hesitates/has no power/idles oddly/has lost gas mileage/does not perform well..."

If you are running platinum spark plugs and notice that your car isn't running right.... take them out and put in NGK BPR6ES spark plugs and see if your situation improves."

My experience is, spark plugs can make a world of difference in how an engine runs. They should never be under-estimated.

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: huptoy</div><div class="ubbcode-body">Where is my problem, is it in the carb or electrical? </div></div> I assume your gas is fresh. Lower voltage spark will cause poor/no combustion. I don't know how both cars would act up at the same time, but I once had a car that burned out both headlights at the same time. I swore it was impossible.

Check your coils and spark plugs on both vehicles. When you are decellerating, your vaccuum is at its highest, air/fuel at its leanest. Makes sense to kick up the idle screw a little.

The battle between platinum/copper spark plugs is VERY interresting. I've wondered about this myself. My EFI engine had a hesitation; sort of a 'dead' spot that went away once I went back to conventional plugs.

Now I find, other clubs telling folks to NOT use platinum for turbo engines. Harley's use the spark plug resistance for 'anti-knock'. Installing platinum negates the anti-knock because of higher resistance. One site claims their cars work best on copper plugs:

DSMTUNERS.COM

"Here's the answer to one of those common questions: "My car stumbles/hesitates/has no power/idles oddly/has lost gas mileage/does not perform well..."

If you are running platinum spark plugs and notice that your car isn't running right.... take them out and put in NGK BPR6ES spark plugs and see if your situation improves."

My experience is, spark plugs can make a world of difference in how an engine runs. They should never be under-estimated. </div></div>

And I can find many other clubs and websites telling people they SHOULD use platinum plugs, so it is a wash. I have had excellent luck with Bosch Platinum plugs in every car that I have used them in, and there have been many.

The website you provided a link to provides a much better explanation of many of the points I was trying to make in my post about the physical and electrical characteristics of various spark plugs. They can and do vary between brands and within brands and good mechanics and tuners will take those facts into account. Do some engines respond better to some spark plugs? Absolutely. The characteristics of the plug should be matched to the engine. But to make a blanket statement such as don't use platinum plugs in a carbureted engine is plain wrong and irresponsible.

Link to comment
Share on other sites

NGK v-groove plugs have always been good to me. I had a 1965 Dodge truck that burned a little oil and would foul out the plugs. I would clean the v-groove NGKs and rotate them once a month and the truck went on beautifully for 3 years! Check your plug wires for shorts or lack of strong spark.

Link to comment
Share on other sites

Guest simplyconnected

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bill_Haegele</div><div class="ubbcode-body">The characteristics of the plug should be matched to the engine.</div></div> My Escort ZX2 runs better with copper plugs than the platinum it came with, Bill. They couldn't be more matched than that. That's my experience. I bought the new replacement Motorcraft platinums, they worked just as bad as the ones I took out, then I tried copper Motorcraft plugs. All my hesitations went away on that four-valve. That was two years ago. Haven't seen a hesitation since.

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bill_Haegele</div><div class="ubbcode-body">The characteristics of the plug should be matched to the engine.</div></div> My Escort ZX2 runs better with copper plugs than the platinum it came with, Bill. They couldn't be more matched than that. That's my experience. I bought the new replacement Motorcraft platinums, they worked just as bad as the ones I took out, then I tried copper Motorcraft plugs. All my hesitations went away on that four-valve. That was two years ago. Haven't seen a hesitation since. </div></div>

As they say, YMMV. grin.gif

The only time I had a problem with plugs was in my 78 Datsun 280Z. As I was modifying the engine, the speed shop I was working with recommended I try the next hotter plug from the heat range I was using. Big mistake. The engine overheated and ran very rough. Went back to the factory recommended plug and heat range and all problems went away. And this was advice from a shop known for tuning early Z- cars.

I use platinums in all my daily drivers (original factory installed in my 07 Ford Edge, dealer installed factory plugs in the 98 Expedition, and Bosch +4s in the 03 Marauder). All run great. I have run Autolite/Motorcraft platinums and copper plugs (not at the same time) in the Galaxie's 390. No real difference in performance. Since I change plugs every 1 or 2 years ( I put maybe 3k miles a year on the car) the platinums increased life has no advantage and the copper plugs are considerably cheaper.

Maybe big, honkin' V6/8s are less sensitive to plug type than small, high-winding straight 4s. cool.gif

Link to comment
Share on other sites

I don't know how we got from a 1931 Hup to Escorts and BMW's??

I wonder if there is a Platinum plug that fits the Hup application without an adapter or other complication.

I think the gentlemans problem could be volatility of modern Ethanol fuel components or a fuel pump anomaly (low pressure) caused by warped or dirty check valve discs, weak or broken return spring, fuel filter contaminated. All these conditions should also affect high speed running even worse?

How about a carburetor idle circuit passage restriction (dirt, varnish, gasket fault).

I know a friend who swears 96% of all fuel problems are found to be electrical related!

A hot spark coil can lose efficiency, so can the previously suspected condensor in distributor.

Does the engine have solid core plug wires? I had a tough one once with a Chrysler 6 that used Aramid fiber core plug wires that had actually "Burned" internally due to resistance at one of the metal terminals at the distributor cap. Result was car started cold and ran fine for 20 minutes then died.

Wait 30 min's and it would restart and run again less than 15 min's?

The Aramid core was burned away for almost 2 inches internally (found by resistance check with ohm meter end to end of each wire, it was the coil to distributor lead). When the coil was cold it had enough power to "Jump" that gap and still fire the plugs until it got hot and output fell off to be too weak to jump the gap.

From experience with driving prewar cars 27 years, I bet it is distributor point or condensor related with spark coil a close second. Substiute known good parts until it is OK.

Stude8

Link to comment
Share on other sites

I just think it is odd that the same owner has two cars doing this at the same time. I'd be asking whats the possible relation between the two cars? Obviously gas if the same filling station was used for both cars. Next most obvious is humid conditions in the storage area if the vehicles are stored in the same place causing corosion on wiring terminals. Vacuum leaks due to bad hoses or loose carb mounts?

What other commonalities can exist between two different makes that wind up with the same problem?

Link to comment
Share on other sites

Back to the original question.

One modern issue that CAN cause the stalling is the use of deathanol fuel. Deathanol does not contain as much energy as gasoline. Being that two of your vehicles have the same symptoms points to fuel. Try talking to the station owner(s) and try to determine what, if any, deathanol percentage is in your fuel.

It is quite common to open up the idle jets in carburetors about 0.002 inch to accomodate the deathanol fuel.

If you can not escape the deathanol, you might try fuel from a different station. Both of your cars will run their best of 87 octane from a name brand station.

Jon.

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: d2_willys</div><div class="ubbcode-body">You don't have an EGR valve, do you? That will do it every time, just read up on defective EGR symptoms. Just a thought. </div></div>

I don't think 1931 Hupmobiles and 1953 Willys have EGR valves. grin.gif

Link to comment
Share on other sites

Guest Bluesky636

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: carbking</div><div class="ubbcode-body">Back to the original question.

One modern issue that CAN cause the stalling is the use of deathanol fuel. Deathanol does not contain as much energy as gasoline. Being that two of your vehicles have the same symptoms points to fuel. Try talking to the station owner(s) and try to determine what, if any, deathanol percentage is in your fuel.

It is quite common to open up the idle jets in carburetors about 0.002 inch to accomodate the deathanol fuel.

If you can not escape the deathanol, you might try fuel from a different station. Both of your cars will run their best of 87 octane from a name brand station.

Jon. </div></div>

There are only two types of fuel sold today with ethanol in them that I am aware of: E10 which is 10% ethanol/90% gasoline (there have been rumors of higher concentrations of ethanol, up to 15% in E10, but that has never been proven and I doubt the station owner would know what the exact mix is that he is buying), and E85 which 85% ethanol and 15% gasoline.

I doubt either car would even start on E85. E10 COULD cause a problem if gaskets and fuel lines have not been replaced with modern materials. Modern materials are impervious to the small amount of ethanol in E10, but there COULD be a long term reaction to the ethanol in E10 over the years.

Link to comment
Share on other sites

  • 2 weeks later...

The 1931 Hupmobile has had the problem for 4 years but it starts easily and runs good. When I start the engine old, I pull the choke about ¾ out, hit the starter for about 3 seconds and push the choke in and it fires up. Cold, I only need to hit the starter. Increasing the idle fixes the stalling problem and is mostly an in convince. The plugs do show signs the carburetor runs rich, even with the air/fuel mixture set at full lean. The timing is correct per factory specifications and I use an electric fuel pump. I have replaced the points, plugs, and condenser about 2 years ago. Additionally, I am not using platinum plugs. I have had the car 8 years and driven a total of 12,000 miles, this is a pretty driver. It has a 70 horse power 6 cyl thaw as reported to cruse at 70 mph but I seldom run more than 55. I have bagged the car for the winter and will address suggestions in the spring.

I purchased the 53 Willys Aero in June and in September was tuned up by an experienced mechanic about 4 weeks before I started experiencing the stalling problem. This car has low vacuum at the manifold but I haven’t identified why. The plugs are not platinum. It has a manual choke and pulling it out ½ it will start immediately when cold. If I touch the gas peddle or the choke when it is warm, I must pump it to get it to start. This car is up for the winter so spring is another time.

Link to comment
Share on other sites

Re the 31 Hup - its possible the electric pump is artificially keeping the carb float level high which will result in a rich mixture, so no matter what you do to the idle mixture adjustment ( and remember its only the idle mixture you can adjust ) the car will idle rich.

As to the Willys - the fact that the vacuum is low is significant, it may well be that you are sucking air in somewhere in the inlet manifold system and leaning out the mixture; this will be more noticeable when you close the throttle to decelerate from highway speeds. Apart from a manifold leak you may well have a leak from any of the vacuum operated items on the car such as power brakes, windscreen wipers, vacuum retard on the distributor and so on.

Lots to consider over winter !!

Link to comment
Share on other sites

  • 2 weeks later...
Guest Bob Kerr

Try this next spring when you get it back out. Get all the tools you will need and Take it out and drive till the problem happens. When it does, immediatly push in the clutch and turn off the key and coast to the side of the road. First check the plugs and see if black or clean. If black it is safe to say fuel problem with carb or fuel. If clean then check for spark. If no spark then you know where to look such as condenser or coil. If you have spark then drop the fuel line and see what comes out. Glass jar works best. Check for water or crud. I have a feeling you may have some water getting sucked up ito a passage or jet when you let off the pedal. What happens if it dies and you pull the choke closed all the way and let it back open? Does it refire? or does it still not run. It will take some doing but you will find the problem if you use elimination. I had some problems with my 23 Olds truck that it would idle only with the choke part way on and at high speed it would run somewhat ok but not so good at normal speed. It was caused by sitting for a few years with reformulated(oxygenated) california gas in the carb and it turned the inside green and some chunks of bright green crud kept clogging all the jets. Runs great now that I have all of it cleaned up, but sure caused a headache for a while.

Link to comment
Share on other sites

Guest Bob Kerr

Hchris does have a good point and I should have thought of that since this past year I fixed three antique tractors(one of mine included) that had running problems with loose intakes, and helped fix two others online that had loose manifolds. All of them straightened right up and ran good after retorquing and readjusting the carbs. Two of those guys were going to spend the bucks and get rebuilt carbs they didn't need afterall. I would check those intake bolts first especially if those engines had been rebuilt recently and while your at it do the heads!

Link to comment
Share on other sites

  • 2 weeks later...
Guest imported_bjr

Do you have a fuel pressure regulator between the fuel pump and the carb? Those old carbs only need about 2lbs fuel pressure to operate correctly, any more then that and they flood out some at idle. I used to own a 32 Hupp F222 that I restored. Mine had an mechanical fuel pump, did yours come from the factory with a vacuum tank to pump the fuel? If so the carb is made to basically run on gravity feed from the vacuum tank, which is almost no fuel pressure. Brian

Link to comment
Share on other sites

I dont know how the distributors are built on either of these cars but I suspect that both have -some sort- of mechanical advance.

I used to have this sort of problem routinely with the distributor on a Pontiac and it was caused by the weights hanging. The pivots would get gummy. Take the springs off, take the weights off, clean the pivots, clean the holes in the weights and relube. Good for about another 7-10 thousand mi - then do over ;-)

The weights werent falling back in and thus the ign remained with way too much advance.... A gasoline that contributes more gum to the system(s) would surely affect both cars also.

Worth a look see....

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...