Stall…vapor lock??

[White Knight]

I just changed my fuel filters and mechanical fuel pump and removed aux tank. Started right up, ran great in the driveway, drove it around the neighborhood for awhile and heading back to house … and it just stalled out. Started right back up and put it in the garage… good fuel pressure, no leaks. Hour later , started right up, decided to take on highway 5+ miles into drive stalled out…. Started right up and went home. What could it be? 302 SVO heads, E303 cam, Holley 650 with electric choke, automatic

 

[bfoldy]

Sounds like it could be. Did you change the routing of your fuel line, by chance?


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[White Knight]

No, starts right up, I could leave it in the driveway and it would run for hours if I let it… and can rev it … all ok. Drive it for a while and just stalls but then starts right back up

 

[Jetfixr320]

Either that or something in the fuel tank blocking the fuel pickup screen?
Im a fan of phenolic carb spacers and DEI heat sleeve in the engine bay and near the exhaust.

 

[MarsChariot]

Assuming it is fuel related and not coil/ignition getting hot sort of thing, maybe all the new hose connections released some small debris that is clogging a float needle or jet??? I hate the ones where you need to risk stranding yourself to test the system every time you do a potential fix. A tough one.

 

[White Knight]

I can sit in the drive way and rev forever or let it sit and it would run until it ran out of gas.if a clogged jet wouldn’t that stop that also?
It is when I’m in drive and especially if I floor it…. Really frustrating and really don’t know where to start. Really appreciate the feedback.

 

[Kalex]

When I had a vapor lock issue I would have to wait at least 10 minutes if not longer before it would start back up. Basically however long it took to cool down some.

 

[White Knight]

How do you resolve it

 

[Kalex]

In my case it was a fuel line that needed to be shielded or moved. It doesn’t sound like you changed your line routings, etc… I’m also not sure if with a vapor lock somewhere would it start right back. Hopefully someone more knowledgeable than I can answer that.

 

[Kalex]

Doubt you did this, but what happens if you put a fuel filter on backwards?

 

[White Knight]

I’m pretty particular about things and check that a couple times before install but of course now I’m second guessing but I would think that if so it wouldn’t allow me to sit in the driveway and rev until basically it ran out of gas. Something about cruising and then accelerating or flooring it that it stalls

 

[gnpenning]

You are confusing fuel demand at idle and little load with fuel demand under load needing high volume. Idling and revving aren't the same as driving conditions. Fuel demands isn't even close.

Basically you need to go back to what you have done and look a little closer while doing some testing. Undo every connection maybe even remove the hose and check for obstructions. When you pull the output side off the fuel pump run the line into a bottle and do a fuel volume test and also do a pressure test. New doesn't mean good (very important to understand this). Do the same after the fuel filter. If it is a fuel related issue you should find it.

If it is something else you were able to eliminate potential areas. DO NOT assume anything, you have to do actual tests for verification.

You mentioned go fuel pressure in the OP, how was this tested?

You removed the auxiliary tank, did you do anything to bypass the selection valve or just turn the knob?

You mentioned filters, how many, where and what microns?

Why multiple filters?

 

[White Knight]

I capped the aux side of the fuel switch and just leave it switched to the main. I have a filter (25 microns) right after the switch going to the fuel pump. Then one right after fuel pump (Earl 35 micron) to carb

 

[Oldtimer]

By fuel switch, you mean factory mechanical valve that twists to allow fuel from main or aux tank?
They are known to leak air into fuel system, but not leak fuel out.
Did you replace all the flexible hoses in system from tank to carb?

 

[White Knight]

Yes the factory switch… I capped the aux side. I didn’t touch lines from tank to switch . After the switch, I have 4-6in new flex line into filter 4-6 in flex to hard line that goes up the frame rail to pump. Hard line was removed, cleaned and blown out before re-installing.

 

[White Knight]

so I remove filters and made
Sure nothing was clogging them. Removed one filter that was from the switch to the fuel pump and now just have one after the pump just before the carb. I bypassed the original mfg fuel switch and ran fuel from tank straight to hard line running to fuel pump. Starts right up and as long as I keep pumping the gas pedal … runs great in park. If I let off the gas it stalls now. Any feedback would be sincerely appreciated

 

[Kalex]

I wonder if somehow in removing that aux. tank your remaining tank is somehow not venting correctly? Also, with this new information it sounds like the problem may be at the carburetor in the idle speed screws or idle mixture screws. Not sure if this is correct terminology as I haven't had much carb experience. Good luck and hopefully some more of these really knowledgeable members will chime in.

 

[DirtDonk]

Why did you replace the fuel pump in the first place?
Did it have trouble? Do you still have the old one?
Just wondering if the new pump is defective and just can't keep up.
You have done all the things I was first thinking of, which is taking a filter out and bypassing the switch. Not a problem that often, but they do act up.
Pumps on the other hand, are notorious anymore.

But not idling now? You didn't touch anything that would have an effect on that, so this is one of those un-reated "coincidental failures" (or more likely "coincidental mishaps") causing your idle issue.
Easy enough to check all the usual suspects. Just give it some more idle adjustment, check the ignition timing, etc.

Not sure what else to check at this point. But I'm still semi-skeptical about any new fuel pump.

Paul

 

[White Knight]

I replaced fuel pump and filters because I switch fuel tank to auxiliary and car stalled so I removed the filters and there was a lot of dirty, rusty, sludge like gas I then so I replace all filters, pump and cleaneD all fuel lines and re-installed. I wonder if some got in the carb and may that’s what causing it to stall out??

 

[DirtDonk]

Unfortunately, that's high on the list of possibilities at this point.
A little cleanup, or pop it open and clean it out, or maybe even run some cleaner through it?

Paul