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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
My camaro fuel pump died several years ago, long story it was parked and sat. I recently changed fuel pump and the external fuel filter, gas was very orange. Drained all bad gas, filled with fresh. New battery, checked all fluids. I tried to start and fired up for 1 second. Now only way to get it to fire is on starting fluid. It’s not getting gas. I hear the pump running. Do I have to purge air from the fuel lines? Or could all use injectors be clogged? Is there any easy way t make sure the gas is getting to the engine? Kind of a novice here?
May take a bit for fuel to make it all the way from the tank to the injectors. Seems like a car with a dry fuel system usually needs about 5 or 6 prime cycles AT LEAST before fuel appears. Hopefully it's only that, and not something like, the little rubber "damper" piece failed, or a bad pump.
By 5 or 6 cycles of fuel pump. Does that mean the few seconds each time I turn the key on. When I do that several times it does start on it own without starting fluid but only for a few seconds then dies. Could the fuel filter and lines have air in them. Do you normally purge them after changing pump and filter. Or does this sound more like clogged injectors from bad gas. I didn’t blow the lines out. Just unhooked the filter and replaced.
Does that mean the few seconds each time I turn the key on.
Yes. Precisely.
it does start on it own ... but only for a few seconds then dies
Sounds like something electrical. The FP relay, or the oil pressure switch section that works the FP.
Not injectors, not the filter, not the lines, not the pump. Although if you didn't change the filter before, kick yourself in the a$$ and do it NOW. I doubt it'll "fix" it but it needs one regardless.
I’m try to check fuel pressure first. Still think it fuel related when I say it runs for a second or 2 it really is just barely running. I keep looking for ways to clean injectors but doesn’t seem to be a easy fix. I ran fine when the pump failed several years ago. My fault for letting it sit so long with bad gas. Totally clean tank and installed new filter. Might try to unhook a return line and see if it’s got good flow as I have no fuel pressure gauge now. Then try harder fixes. Thanks
More then likely there's barely any fuel making it through the lines at all. Fuel gets ole and crusty so fast these days. I would check fuel pressure n then start pulling lines off to see if you can blow through them. FPR maybe all gummed up as well.
Update: no pressure at schradar valve, I don’t have a pressure gauge but when I depress the pin. Almost nothing come out. Next I unhooked the main line in under the hood, turned key on for a second. Nice flow out. So lines under car and pump are fine. Where is the regulator in relation to the schradar valve, what comes first? Is there any way to use some cleaner to break up what’s in the top half of lines. Can I fill tube up with carb cleaner and hand pump fluid to loosen it up. We’re getting there.
Fuel comes from the pump, up the pressure line, into the end of the fuel rail on one side and out the other end to the other fuel rail in the same way, then the regulator is at the very end of the whole under-hood part of the system. It lets enough fuel drain back to the tank through the return line to limit the pressure to whatever it needs to be. Fuel doesn't go "through" it to get to the injectors. The Schrader valve is on one of the fuel rails, specifically the 2nd one in the chain, therefore before the regulator. The FP itself is basically "constant volume": it constantly pumps the same amount of fuel, and pressure is developed only by way of the restrictions of the injectors and the regulator. More fuel is allowed to return to the tank at idle to keep the pressure steady, and less at high RPMs and high power demands, at which time most of the fuel ends up going through the injectors and into the motor, and relatively little through the regulator and return line. In fact if the regulator is plugged up, the FP will go EXTREMELY high, especially at idle, when the engine's fuel requirements are low. If it's stuck completely open, the FP will be very low. Which might be your problem.
When you say "nice flow out", what are we talking about here? It should be almost like a garden hose.
Yes the flow was like a garden hose. It didn’t shoot like 3 feet but it was a lot of volume and came out like a foot and thick like a garden hose. I could hook supply line back up. Unhook return line out of fuel assembly and if it has good flow. That would kind of confirm a stuck open fp regulator, I think. What does the schradar measure. If the regulator was stuck open. Wouldn’t gas still come out of the valve? I pressed the nipple inside and just a drop came out.
Last edited by Jonb1032; Sep 14, 2020 at 06:22 PM.
If the regulator is sticking open, fuel may not necessarily flow from the Schrader valve since fuel can flow back to the tank via the return line with very little restriction. Disconnecting the fuel return line may only reveal whether fuel is flowing, but will not provide much information about the system pressure. A gauge would be a very useful tool at this point, as the Duke of the Davenport metioned in the second post.
If there is return flow it may be possible to restrict the return line and create 30-50 PSI of line pressure to see if the engine will run without supplementary fuel or starting fluid, Carefully pinching the return line may allow the pressure to be regulated close enough for diagnosis.
It is also possible to remove the pressure regulator to inspect/clean it, but that requires removing the plenum.
My 89 formula 350 just did this last week. She’s running now. I had code 34, disconnected the MAF it changed to code 33. Replaced
still no start without brake cleaner sprayed into plenum. So went to harbor Frieght, 15$ fuel pressure gauge, had 40 psi. (good) also lsxmatt has good videos on you tube.
next used a noid light checked out from autozone, it checks that the signal is sent to injectors to eliminate the ECM as possible culprit. Mine checked out ok.
next checked OHMS on injectors. Supposed to be 16. One was 5... ordered 22 lbs injectors from injector connection 412$ with new gaskets. She does burnouts now... try all that.
Update, I had a neighbor borrow a fuel pressure gauge from another friend, so we tried the hook it up to the schradar valve. Mind you we have limited knowledge, but we could not fit it. There were a few fittings but none had a center that would press the pin down snide the schradar valve. They were all hollow. So I said forget it, ordered a new fuel pressure regulator, some new intake gaskets. After I install them I’ll see what happens. I want to thank you all for helping me, I’m sure after I install these new parts, I’ll have more questions. It’s my own fault for letting her sit for so long, sometimes life gets in the way. Here’s a pic when she was in her hay day. Thanks again.
Don’t part swap, it gets expensive. See if auto zone has the loaner tools you need. Instead of buying a possible regulator you don’t need just buy the cheap set from harbor Frieght.
do you have the original injectors on it? The Multecs (grey) should be swapped out if they are the same as mine.
Tuned performance guided me on my thread. He’s great, a wealth of knowledge. Maybe go to we’re my post is next if this doesn’t fix it next.
Update: the fuel pressure regulator was the culprit. It was very chalky and stuck in there. I replaced it. Fires up. Now the schradar valve when pressed squirts up with gas. It’s running but seems to be missing a little. A back fire now and than. I’m going to check plugs and see what they look like.
