Intermittent Fuel Problem

[Steve_Mack_CT]

Finally ready to deal with "vapor lock" or whatever you want to call these symptoms - this is an intermittant problem but can be a pain.

hard starting when cold - needs starting fluid or a lot of cranking, especially if it sat more than a couple days. Starts immediately with the fluid - so I do not think ignition is an issue at all.

Runs fine when cold, but if idling in hot weather too long, the engine will stumble a bit. Running along at say 45 mph all day long is not a problem. When it does stumble, it really feels fuel starved.

Engine will start again no problem if it cools a bit, but can give trouble if it is really hot.

I was in a long parade yesterday, and got through it no problem, but ran a few blocks up the road, (by then the temp was pretty high) and when I pulled off to the side street and let the throttle off, it stalled and needed a few minutes to cool down enough to restart.

I see carb and gas line get really hot - so I figure the gas must be boiling either in the bowl or lines. I have a small leak on the two part manifold under the carb and I suspect this is adding to the heat.

Strategy to address is as follows:

Fix manifold leak, set fuel bowl a tad higher, insulate fuel line and install electric fuel pump. Here are a couple related questions:

Anything in particular to watch out for in removing manifold? bolts to block look fine, but the two part manifold looks like it will be a job to separate. I fugure heating it up but any tricks out there for this? I should have done this last year, but did not think it was that big of an issue, I am now thinking it is adding to the problem or may be the main problem?

On the electric fuel pump, I know a tandem arrangement is best but do you bypass the stock pump and meet up after it or should you run the fuel right through that pump?

Carb and stock fuel pump have been rebuilt and function fine otherwise. Anything I may have missed?

Thanks, Steve

[West Peterson]

I run my electric fuel pump in line, and only turn it on when needed. However, I feel that my mechanical fuel pump is in need of rebuilding, as I'm getting that "stumbling" too often when it's not even that hot out.

[Steve_Mack_CT]

Hey West - can you tell me whose pump you used? I have one from Hirsch but it seems to me (without hooking it up) that fuel would not pass through it if it was not running. I would prefer in line as I already have a break in my fuel line and it would be a little easier/cleaner to install.

Thanks, Steve

[West Peterson]

The one everyone seems to like is the Airtex E-8011 that is available at several auto parts stores such as CarQuest and Napa. No pressure regulator needed. There is another recently introduced version of this 6-volt unit available, and it puts out slightly less pressure (E8902-2). Roughly $50.

[Steve_Mack_CT]

Thanks West. Got the Airtex pump. Another question for anyone who has used this - I have a break in my line that just happens to be near an existing (factory I assume) hole in the frame where a fuel filter was - in other words, ideal place to mount this except it is near the front of the RH front door. My understanding is closer to the tank is better, but I may try this first to avoid drilling any holes for the mounting bracket, and the line is already cut there. Anyone have any thoughts on this? I guess I can experiment but if there is a compelling reason the pump should be closer to the tank I will just do it that way.

West, BTW you probably have the experience but FYI the vacuum fuel pump rebuild is not hard to do. I used "Big Kev's" from Packard Info's step by step guide, set up a lap top in the garage - different model pump, very simillar design. Took a couple hours including removal, cleaning and installation.

[West Peterson]

Steve

I have mine mounted way up front. Yes, probably should be near the back, but since I only use it when needed, I believe it's fine where it is.

Did you get the E-8011 or the E8902???

Thanks for the advice on the fuel pump rebuild. I'll print that out and give it a whirl. I know it's just a case of a couple of the diaphrams needing to be replaced.

[Steve_Mack_CT]

West, I have the E-8011, and intend it only for when I need it also. I would rather take a stab at it up front and avoid drilling any holes!

On the vacuum pump I had one minor problem only - the "impeller" or lever driven by camshaft is a three part unit, I thought I could kind of fish it back together once the pump was reassembled but you cannot do it that way, you really need to put it back in place when putting the pump together, so some tedius unbolting the diaphrams, lesson learned.. Kev does not cover this in his overview, but for the most part it is intuitive...

How did your RF fender repair come out, BTW? Did you ever post the finished product?

[West Peterson]

I thought I did.:confused:

This is it, as I'm trying to refit the rear fender so that it connects to the running board. Whoever worked on it last, messed it up.

[Guest billmeyer]

My 1950 Dodge Wayfarer suffers from vapor lock (at least I think that's what the problem is) when I attempt to re-start the engine after it has been off for more than a few minutes but while it is still hot... especially when the outside temp is in the 90's. It absolutely refuses to start until the engine has cooled down... several hours later. Once running, it runs fine and cold starting is not usually a problem. The fuel pump is a rebuilt unit and the carb was professionally rebuilt. I'm thinking about installing an Airtex E-8011 electric fuel pump... as near the gas tank as possible. Do I leave the mechanical pump in place? And should the electric pump be left on at all times when running? Your advice would be appreciated!

Thanks!

[West Peterson]

Leave your mechanical pump in place. Only turn on the electric pump when you start having problems. If you stop for gas when it's hot, turn the electric pump on for 15 seconds or so before attempting to start. Then, after it has started and you're moving along nicely, turn it off.

[Guest billmeyer]

Thanks so much, West, for your advice. The problem has occurred before but it came to a head last weekend when I signed up for a big annual parade here in my home town of Fort Scott, KS and, after lining up, turned the car off for a half hour until the parade was about to begin. My two little grandsons were with me and were looking forward to the big event! Not to be. The temp was in the 90's and the ol' Dodge wouldn't start. They sure were disappointed. I went back about 4 hours later and it started right up. Other than this, it's a fine running car but this has been a vexing problem, to say the least! Thanks again.

Bill Meyer

[West Peterson]

The worst is when you're stuck in traffic during rush hour, in the middle lane, and not enough fuel is pumping through so it sits there and percolates. It's very nice to be able to flick the switch to an electric pump and be able to keep it running. I imagine that your vehicle would probably have quit during the parade. Parades are not good for old cars, and I avoid them like the plague.

I understand how badly you felt for your grandsons.

You might want to consider rebuilding your mechanical fuel pump, as I have decided to do. Antique Auto Parts Celler (Then & Now Automotive) sells wonderful kits. I suggest you go to their website to see just how they've solved some problems. (www.then-now.com)

[Steve_Mack_CT]

Quick update now that we are into summer and I am seeing more posts relating to "vapor lock" and such. The electric fuel pump and insulated fuel line helped a lot, but in bringing the car to a trusted friend and experienced mechanic a couple weeks ago I found I missed a couple of key things - my auto choke was sticking & the heat riser butterfly was also sticking, one issue causing hard cold starts, the other (heat riser) really adding to the issue of drivability once fully warmed up. Both of these were pretty easy fixes, and made a world of difference. I am fairly comfortable and handle most mechanical tasks myself - but still missed these basics. So I guess I am saying be sure to check the basics (we also checked ignition side as well, which was fine.) and a simple adjustment or two can go a long way as well.

I am finding I rarely need the electric pump now and it has been really hot here in CT - but of course now running fresh mechanical pump and fully rebuilt carburetor...

Now, if only I had Air Conditioning....

[West Peterson]

I feel that my butterfly is kind of sticky/stiff. What did you do to free it, and make it work the way it should?

[mrpushbutton]

I feel that my butterfly is kind of sticky/stiff. What did you do to free it, and make it work the way it should?

It may be bent somewhat, If you have occasion to have the carb apart roll it on a known flat surface.

[Steve_Mack_CT]

Well, if you mean the choke butterfly we found the hang up was not the butterfly but the little piston that controls the automatic choke - that was stuck so we took it all apart and gently cleaned it up just a bit. Not sure what other years have this type of arrangement, but when I first rebuilt the carb I never took that apart - kind of like a black box to me! Well, it is really a pretty simple arrangement. Working well now.

The butterfly on the heat riser was simple - WD- 40 and working it loose. Not like a rusty bolt, it seems like it does not take a lot to get it to stick but it does not take a lot to loosen it either. I plan on checking it regularly, and even with the heat the penetrating oil really does not seem to burn off or smell, so I would not be shy about using it there. I suspect that hung up over the wintertime.

Mr. Push's idea is one I had not heard of before, makes perfect common sense and will file that away for checking out butterfly with next carb rebuild. Proof of the value of this forum once again!

I still need to address the exhaust leak as there is a two part manifold on the '39 120, but with the heat riser valve opening properly now, that has become a minor issue again - there is no restriction there, which probably made a minor leak more of a problem. I don't really want to lay the car up because when I do this I want to blast and paint the exhaust manifold, and would rather do that over the wintertime.

[West Peterson]

Thanks. Yes, I meant the exhaust butterfly. I've "unstuck" it, but it still seems like it's kind of binding after "playing" with it a lot.