Projects New Project: 1953 Oldsmobile

I'm wondering if the gas cap is the issue. I believe my old Lark gas cap is vented, which I think would prevent such a vacuum from forming. To check, maybe you can open the case cap the next time you experience this symptom.

 

That sounds reasonable. Anyway to check by looking at the gas cap itself?


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When the fuel pressure goes down, just remove the cap and listen for a sucking sound as the tank refills with air. The fuel pressure should immediately go back up as the cap is removed. If that is the problem.

 

Ok, as per usual, I’m lost.

Drove out to Summit Racing today to get some seatbelts. It’s about a 2 hour drive for me (went for be fun of it).

Car drove out all the way just fine. On the way back, I get about an hour down the road, and the fuel pressure dives. I stop and get gas hoping that’s all, car did ok for a while.

Got back in town, and as soon as I hop off the highway, fuel pressure can barely keep the car running.

I meet my wife about where I’m at, and let the car sit a bit while we go get something to eat.

Come back to the car and drive home, close to home pressure starts acting funny, but I make it with no actual issue.

I’ve been playing with the car for a couple hours now. I’ve replaced the fuel filters (that looked fine), I’ve blown out the fuel lines (that were clean), I even pulled the pump and cleaned out the screen (which had a little dirt, but not really any).

I just added my check valve. It’s located between the pump and the pressure regulator (good spot?).

The check maintains pressure between the check and the carb (also ok?).

My only concern with having the check now, is that I may not see the pressure drop coming on as quickly. But my bigger concern, is that I really haven’t found anything wrong. So what gives? Any more ideas?


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So, you did the gas cap trick? Any difference? The symptoms could be related to a vapor lock issue but I do not believe it is that hot on the highway in TX yet. Refresh my memory....this is the electric pump we are dealing with here?

 

Yeah, tried the gas cap trick with no improvement.

About 9 months ago I traded over to a Holley red pump. Things have been fine till this week. I’ve checked everything I can think of. My only other guess is to swap the pump. I’ve got a cheap Edelbrock pump I could try out. Seems nuts that a Holley would go out that fast though. It’s mounted to the frame well below the tank as close to the tank as possible.


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If the engine is running poor, the fuel pressure can read low. If the car has an HEI distributor, I'd look at the ignition module first and they are inexpensive. A bad one will do some funky things to you and almost always, once the car cools off it works fine. Some, the car will shut off dead, I had one that would allow the car to run for 300 feet at a time. The last one if I shut the car off for more than 20 minutes, it wouldn't start until it was completely cooled off. So if I was running errands, I had a 10-15 minute window to get back in the car and have it start.

 

If that were the case, wouldn’t I still have pressure between the carb and pump? I figure the pump doesn’t care if the engine can run or not. The engine never stumbles until the pressure hits 0.


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Where is the filter that you mentioned finding debris in?

 

None had much, but the one that had more was between the regulator and the carburetor.

Which made me start thinking, maybe it’s a bad regulator? Only reason I’m thinking this, is because I’ve got my pressure gauge between the regulator and the carburetor.

I may put another pressure gauge between the pump and the regulator.


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Edit: scratch that. Bypassed regulator and same results.

Now I just bypassed the fuel tank AND the regulator and ran a gas can off pump. Same shit happening. My edelbrock is dead, so I can’t try a new pump.

 

the reason I asked about the filter is there should be a filter between the tank and the pump. Electric pumps do not like any debris and can/will kill the pump in time. Here are the instructions from Holley with the note about the debris
https://www.jegs.com/InstallationInstructions/500/510/510-12-125.pdf

 

Gotcha, well the filter after the pump had more crap in it. So let say I killed the pump, do I need the rebuild kit with the new vanes?


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I would check with Holley on rebuilding. Also, while there ask for a recommendation on a good high micron filter. In the meantime you could install a filter to begin catching the debris if the existing pump works at all. There is a chance it will help keep the pump running but it is somewhat doubtful at this time.

Link to a Holley page shows a relay required which begs the question how you wired this pump in? If you ran a light wire feed to the pump it could be overheating due to amp draw. Might want to add that relay and ensure a good quality source of 12 volts is available at the pump
https://www.holley.com/products/fue...carbureted_electric_fuel_pumps/parts/12-801-1

 

Why not use the stock mechanical pump? No pressure regulator needed. You may have covered this but I'm too lazy to re read 12 pages to find it.

 

Wow!!!!. Just finished reading your whole thread, I now have a dull headache. You,my friend have been through HELL,your car(Beautiful Car,by the way)you’re illness,you and your Dads recovery. Your persistence and drive give the rest of us the hope to keep at our car projects. Wish you and your family all the best.

 

Ok ok ok... more answers keeps meaning more questions.

Called Holley this morning. Described everything going on to them, and they agreed the pump seemed like a likely culprit.

I went through the whole thing tonight, and even the motor itself.


The top end was loose and there was a bunch of crap inside the motor. I cleaned everything up, put it back together, and still had the same g*d d**n f***ing problem.

*ahem*

Anyway. The motor at least ran more quietly after I was done.

Still thinking it could be the motor, I borrowed one from a friend and hooked it up. Still continuing the same problem.

It has GOT to be something in the tank (again). But I’ve been pretty confident in every solution I’ve some up with so far. Haven’t had a winner yet. I’m stressing a little just because LSRU is coming up fast. It’s a big deal to me to make it.

Going to drop the tank tomorrow after work. I’ll keep you guys posted.

Thanks man!



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What. The. Crap.



I have now dropped the tank and checked it. Looks fine. Decided to try running the car with the tank outside of it so I could look for problems. Damn thing ran fine.

Time to keep searching.

Groovy.


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Couple thoughts…..the pump looked pretty messed up for being relatively new. I see a filter at the tank in the pic. Has that been there since the pump was installed? Is there another up at the carb? When you replaced the rubber fuel line did you use hose that is designed for our new wonderful ethanol blends? What did the debris look like that you found in the filter, black particles or rusty junk? And lastly tell us how you wired that pump in and to what tie point, what gauge wire etc.

 

I called Holley a second time when I took the pump apart because it was so gross. I told them about all the junk on the motor side, and the tech didn’t seem surprised at all.

The filter before the pump was not always there, which is why I though I killed the pump. It didn’t get added in till about 4 or 5 months in. I cleaned the pump screen at that time too. There is also one at the carb. Holley recommends 40 micron before the pump and 100 after.

The fuel lines are basic rubbers I got from Summit. I assumed everything made now was for ethanol pump blends. Maybe I’m wrong. The crap in the filter was rusty looking.

I ran my wiring setup by Holley as well, no complaints from them. I even had a volt meter at the pump while the pressure was all over the place, voltage was constant. I’m running a relay up front with roughly 16/18 gauge wire to the back.

Here’s my current thought process: There either has to be crap in the tank I can’t see or a break in the line between the pump and tank I can’t see. Here’s what I ordered last night:

I’m going to add a screen to the pickup tube and replace the line from the tank to the pump. Even when I drained the tank into gas cans, I could hear the pump struggling. Maybe something moved when I dropped it from the car.


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good parts order. I would not like to run a pump on 18 ga wire, just me....I am anal about current draw when voltage drops a bit for any motor. If I were a betting guy I would say that pump when run for a longer period of time is going to be the culprit along with debris in the tank which you have found.

 

I would not use that glass and chrome fuel filter. There has been problems with them leaking and fires. Use a good metal can type.

 

good point BJR^^^^^^

 

Dang. Still having issues, but now I’ve got a new one in the game.

I got my parts today, and put everything back together. Pressure seems to be fine mostly. Still wobbles a little, but mostly under heavy acceleration.

Took the car for a test drive and it did good for a while. Pressure never dropped, but as soon as I let off the accelerator, the engine would try to die out. I could stay on the throttle and keep it going. If I let the car die out, it was not happy about starting and would start rich/blow smoke for a second.

Think I damaged the carb while playing with the pressure for a few days? Engine would die with no pressure loss from the fuel pump.

Also wondering if bobss396 had the right idea. Here’s what he said:

I initially wrote it off (sorry man) because the pressure loss didn’t make sense to me. But now my car acts like it’s flooding. I can kill the fuel pump and keep the car alive, or stay on the gas.

May try new plugs and hei module. I’ve got a friend that can rebuild the carb for me if need be. I’m still determined to make LSRU.
(Why does crap keep happening before shows!?)

Also on another note, I want to stick with the glass filter before the pump to keep an eye on things while I’m working out issues. It’s not well made, so once I’ve got everything ironed out, I’ll swap it.


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You have gone this far now with the fuel system so I would pop that carb off and look at it. wouldn't take much debris in there to cause issues.

 

With the luck you seem to have, I would not risk the glass fuel filter. Don't want your next post to be telling us it burned to the ground.

 

Maaaaan.... you’re probably right.


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Also, before I burn more of the money I don’t have...

If the engine floods at idle, and I can kill the fuel pump to save it, does a carb rebuild make the most sense? I’ll swap the coil and plugs anyway, but LSRU is coming up fast.


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If the carb is flooding it may just have a piece of crap between the needle and seat. Just take it apart and clean it, no new parts necessary. Double check the float drop and level settings.

 

I decided to drop to carb off for a rebuild. Should have it back in a few days. Really hoping that’s the final issue. I’ve already decided that it’s LSRU or bust. I’ll slap the car back together and go for it. Worst case scenario, AAA will get us back home and then we can go in a boring car.

Anyway, while I’m waiting, I installed the seatbelts I got from Summit. My car is now 100% safer. It’s got belts AND it doesn’t run. Haha


Soooo.... I don’t believe I’ve mentioned it in this thread at all, but the Olds does have a name. My wife suggest Baloo when we got it, and I loved it. It’s the only car I’ve ever named and genuinely used the name. I mention this because I’m super excited about what I ordered for the buttons on the seatbelts...


They’ll be in next week. I’ll post a picture once I’ve got them on.


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My 34 flooded when I first got it together. I reset the float level in the AFB and it was a little better. Bought a fuel pressure regulator and set it at 5 PSI...perfect! No more fuel problems.