General Fuel Pump Question

[JohnD1956]

Regards a manual fuel pump, in this case, the one on my 78 Wagon.

After a installing a new one several weeks ago, immediately there was an intermittent clicking noise which sounded just like a noisy lifter. The thing is the noise seems to be audible in the right rear corner of the car. My question is if anyone has ever experienced this with a recent fuel pump and could it be a sticky pressure relief valve in the pump? Here are some charisteristics

As indicated, the noise is intermittent. I drive this car 10 miles to work and another ten miles home 5 days a week and it happens every day.

It happens at an idle and while cruising. It seems to go away if you open the carb, leading me to think it may be the pressure relief valve when the carb bowl is full. But I don't even know if that's possible.

I used my stethoscope and while I could hear the noise when I touched the frame of the car, especially in the return fuel line, and it is more audible at the right rear of the vehicle.

With the stethoscope I eliminated the pumps, alternator and compressor as culprits. But I also did not hear the noise with the scope directly on the fuel pump.

It happens if the car is moving and if the car is not moving. It usually happend a few seconds after the car is started and while it's warming up in the driveway. It's frequency does seem to be tied to engine RPM.

I also eliminated valve train noise and bearing noise. Again, you can definitely hear this clicking when you put the scope on the frame of the car?

The engine runs very well. It is smooth and I have no hesitation or missing at any engine rpm.

This car has a new gas tank, but I can't remember if I put in a new sending unit too. I also stopped the car and opened the gas cap just to see if there was pressure in the tank from a blocked vent, but that was not the case.

I do not smell raw fuel anywhere around the car either while it's running or off, so I don't think I have a bad fuel line. But that may still be a possibility as I have not replaced the gas return line or the canister purge line.

I drove that car this entire summer without any such noise, and the noise did not begin till the FP failed a few weeks ago and I replaced it. So I'm sure it's fuel pump related, I just hate to do another replacement wind wind up with the same thing.

I am begininng to wonder if this is not the same issue with the clicking noise I get on my 56. I still cannot find the source of that intermittent noise. But I'm wondering if that is a like wise fuel pump issue. But that's a different story for a different day.

[JohnD1956]

Well, I should have read my manual first. There is no pressure relief valve. There is a "metering outlet" for a vapor return system. This vapor return port is on the positive side of the fuel pump according to the diagram. For it to work the FP's valve have to be working right and since the car runs right, it does not appear to be the problem.

Gotta do some sleuthing tomorrow. This clicking is driving me crazy,

Edited January 5, 2013 by JohnD1956 (see edit history)

[JohnD1956]

Follow up:

After reviewing the manual in detail last night I thought I had a mis routed vacuum hose to the valve on the emissions charcoal canister. Checking for that this AM I discovered that I had the vacuum source to the air cleaner thermac and emmisions canister disconnected. Hooking that up however did not solve the problem.

While running the noise began again and it was audible outside the car at the right rear so I jacked it up and crawled underneath. There were no leaks and nothing loose as far as I can tell so I grabbed the lines going to the tank and immediately felt the pulsating of the gas in the main fuel line in rythm with the noise. The fuel return line had a similar pulse but very weak ( as expected) and the vapor line to the emmisions canister was pulseless.

Returning with the stethoscope I could feel the pulse and hear the clicking in the fuel line side at the fuel pump. I also head the click in the fuel return line, and further probing at the pump I heard the click in the lower half of the pump, not the upper side.

This car does have a newer metal fuel line up the frame rails, so I suspect the inlet valve is not properly seated or staked in the fuel pump and I'll probably get another new fuel pump for next week, when the weather is supposed to warm up a bit.

One thing that really bothers me it is doing things twice, or more, because of lack of integrity on someone elses part. The only thing that bothers me more is doing things twice or more because I screwed up.

[jscheib]

John,

Good work in following the leads and hope the noise gets resolved. Or, I supose you can turn up the radio and wait till the car stops, as an alternative.

John

[60FlatTop]

You might have a weak pump arm spring or a sticky pivot pin. If it was mine I would loosen the pump bolts and turn them finger tight. Then while the engine is running and clicking back them out enough to take the arm off its actuator cam. Just run on the carb (nice to have a reserve instead of FI) If it stops return the pump. Or just take the pump back. Most counter guys will give you a replacement without question. They do it all the time (a hint).

Bernie

[JohnD1956]

Yes, that's what I'm doing. If it still does it then I'll run a temporary fuel return line. Maybe that thing has an internal blockage.

[Smartin]

Does the pump arm have a metal "plate" on it that rubs on the cam, instead of just the bare arm itself? I was thinking about it possibly being that plate is loose and clicking. I would probably just replace the pump first, though.

[JohnD1956]

I've seen those fuel pump arms, and I can't remember if this had one like that or not, but I don't believe it did. I just finished replacing that piece of flexible fuel line from the tank to the metal line. I thought maybe the flexing was colapsing the line and causing the noise. I had mixed results.

Let me preface by saying; a prior owner had run a flexible fuel line the length of the car in the past and I salvaged most of that when I replaced it with steel a few summers ago. Then, when I put in the new tank two years ago (and btw, I can see I also put in a new pickup unit at the time) I used a piece of this salvaged flexible line for the 18 inch stretch between the tank and the steel fuel line.

This piece of line was now obviously breaking down and it was extremely pliable. I assume that is from the ethanol in the gas. You could feel the fuel being drawn through the line while the engine was running. While I was under there I crawled a bit further to check the lines where they run up the engine side of the rear frame cross member. When I put in my steel line I put a union there and ran a short piece of line up over the rear cross member to the original location of the fuel line. That union appeared to have a small leak. And even though I put a line bracket right in the area, I could just move that union a small amount where it hit the rear cross member and made a similar metallic click like I've been hearing.

So I thought this was the source of my noise. Maybe the new pump was just that much stronger than the one that recently failed, and was causing this ?

Unfortunately I did not have a new piece of flexible line around here when I started this little project, so I used another piece of this same flex line. The new piece of old line has no flexing in it whatsoever. It feels solid when the engine is running. I tightened my union and put a piece of pipe insulation between it and the frame too. The early result of the test drive around the block was very nice, but just before I got back to the driveway I heard the clicking again.

But I also have a piece of this salvaged line in the front by the pump, so I'll get some new type line ( probably fuel injection type line), and replace that this week. If it stays this warm (41 degrees today), I'll go back under and replace that line with some brand new flexible line too. I may even put another short piece of steel in there to cut down on the 18" distance to the tank. That seems really excessive to me.

[JohnD1956]

After replacing the gas line at the fuel pump the noise has all but totally dissappeared. At this point I am wondering if this is something I'll have to just live. The manual shows that the original Buick motor pump is rated for 3 lbs. Those pumps are no longer manufactured today. Instead there is now one pump to replace many different pumps and the other engines call for pumps rated from 5 lbs to 9.5 lbs. Since I can now cover what little noise remais with the radio I'm just gonna drive it and re evaluate in the spring.

Pretty weird though, deteriorated flex gas line, who'da thunk?

[Dandy Dave]

Ethanol raises the devil with everything. I can see the higher pump pressure also being part of the problem. I had a Leland tractor several years ago that we could not stop the carburetor from flooding over because the replacment pump put out to much pressure. I pulled it apart and replaced the spring with a lighter one. A frustrating Problem solved. Dandy Dave!

[JohnD1956]

Well it was too good to be true. The noise is back. I even replaced the rear fuel line again with new gas line. Dave, I do not think one can get a newer style manual pump apart to change the spring but I say this admitting I never tried to take one apart. I know my 56's pump is bolted together but the 69 and 78 has a pump where the casing appears crimped around the diaphram area, and I don't think it comes apart readilly. Unfortunately I threw away my old pump from this job or I would have tried to see if I could at least get the arm out of the housing. The old pumps arm and the new pumps arm are definitely shapped differently, and maybe that's all I need?

But I recently heard of another potential fix. Factory fuel lines come with quite a few twists and turns. When I put the replacement line in this car I just ran the line straight. It seems that some of those twists and turns actually create a spring for the fuel and eliminate, or at least mitigate, the surging of the fuel in the line. So It would seem I might need to replace this line again and build back in as many twists and turns as I can. I will await spring for that as we are forecast to return to our regularly scheduled winter tomorrow.

I'll also pick up another pump and if we get a nice day somewhere I'll change the pump again just to see if thats the culprit. But I doubt it's the pump itself. We'll report back when I get further into this.

[FLYER15015]

John,

Two ideas for you to consider.

1. Install a fuel pressure regulator. Try Summit Racing plus others.

2. Try an old racers trick. take a coffee can and wind 1/4" copper tubing with about 10 turns on the inside and solder together. We used to make these for stock cars, and drop some dry ice in them prior to the race. We also filled the oil bath air cleaners with naptha we picked up from the dry cleaners on the way to the track. Just like NOS for the first couple of laps.....

Mike in Colorado

[JohnD1956]

I could almost see a pressure regulator Mike, but that would only impact the system after the fuel pump. The noise and problem I have is between the tank and the pump, on the suction side.

The other system sounds like you were trying to get the fuel colder? Not quite sure how that would help this situation?

[Dandy Dave]

I know your right about the modern pumps JD. They are sealed units. On the old take apart units, you needed to push down and turn the diaphram 1/4th of a turn after taking all the screws out. I've used the regulators before that mike mentions. It may work in your given situation.

Mike, NOS is a general term around old car buffs for, "New Old Stock." Do you mean N2O for Nitrous Oxide? Dandy Dave!

[FLYER15015]

You are right Dave. I was typing too fast.

Speaking of chemistry, if you drink too much water, could you get dihydrogen monoxide poisioning ? Really old joke.

Mike in colorado