Low Fuel Pressure
Thread Starter
2nd Gear
Joined: Apr 2015
Posts: 2
Likes: 0
From: St Augustine FL
Low Fuel Pressure
I've had 3 C3's and am new to the C4 technology. Bought a '87 that had been sitting a few years. Got it started and drove it before I bought it about a month ago. Trailered it home: cranks but won't start. Decided to pull fuel pump assembly and was SEVERELY corroded with holes. Replaced it and car started right up and ran fine the first day. Next day: same symptoms. Cranks and "wants to run" but doesn't. Acts like it floods out. When I check the (I think it's called Schraeder Valve) on fuel rail, no fuel squirts out.
I also have one code #34, MAF sensor. At this point I'm thinking fuel pressure regulator.
Could the MAF tell the computer to stop sending fuel thus causing a no start? Or could the FPR cause a no start.
I think I'll pull fuel pump assembly back out to inspect because it's so easy, but any ideas would be greatly appreciated.
And, thank you for letting me join your forum - it's awesome.
Steve
I also have one code #34, MAF sensor. At this point I'm thinking fuel pressure regulator.
Could the MAF tell the computer to stop sending fuel thus causing a no start? Or could the FPR cause a no start.
I think I'll pull fuel pump assembly back out to inspect because it's so easy, but any ideas would be greatly appreciated.
And, thank you for letting me join your forum - it's awesome.
Steve
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
I've had 3 C3's and am new to the C4 technology. Bought a '87 that had been sitting a few years. Got it started and drove it before I bought it about a month ago. Trailered it home: cranks but won't start. Decided to pull fuel pump assembly and was SEVERELY corroded with holes. Replaced it and car started right up and ran fine the first day. Next day: same symptoms. Cranks and "wants to run" but doesn't. Acts like it floods out. When I check the (I think it's called Schraeder Valve) on fuel rail, no fuel squirts out.
I also have one code #34, MAF sensor. At this point I'm thinking fuel pressure regulator.
Could the MAF tell the computer to stop sending fuel thus causing a no start? Or could the FPR cause a no start.
I think I'll pull fuel pump assembly back out to inspect because it's so easy, but any ideas would be greatly appreciated.
And, thank you for letting me join your forum - it's awesome.
Steve
I also have one code #34, MAF sensor. At this point I'm thinking fuel pressure regulator.
Could the MAF tell the computer to stop sending fuel thus causing a no start? Or could the FPR cause a no start.
I think I'll pull fuel pump assembly back out to inspect because it's so easy, but any ideas would be greatly appreciated.
And, thank you for letting me join your forum - it's awesome.
Steve
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Go to your auto parts store and "borrow" a fuel pressure gauge and hook it up to your fuel rail. When you turn on the key (but don't start the car) the pressure should immediately build to 39-43 psi and HOLD. If it does not build, check the fuel pump. Did you reuse the pulsator? If you did, guessing that it has slipped of the fuel line. Replace it with a piece of fuel hose and two clamps.
You can check the FP regulator by removing the vacuum hose from the regulator and check the hose to see if there is fuel in the hose.
You can check the FP regulator by removing the vacuum hose from the regulator and check the hose to see if there is fuel in the hose.
Thread Starter
2nd Gear
Joined: Apr 2015
Posts: 2
Likes: 0
From: St Augustine FL
Pulsator
Go to your auto parts store and "borrow" a fuel pressure gauge and hook it up to your fuel rail. When you turn on the key (but don't start the car) the pressure should immediately build to 39-43 psi and HOLD. If it does not build, check the fuel pump. Did you reuse the pulsator? If you did, guessing that it has slipped of the fuel line. Replace it with a piece of fuel hose and two clamps.
You can check the FP regulator by removing the vacuum hose from the regulator and check the hose to see if there is fuel in the hose.
You can check the FP regulator by removing the vacuum hose from the regulator and check the hose to see if there is fuel in the hose.
When I try to crank the engine it almost catches but then I check the valve on the fuel rail and nothing comes out. I would think gas should squirt out or at least run out a little. But it doesn't.
After cranking, I pulled little hose off of fuel pressure regulator and no gas.
Then, I played with the hoses going to and from air control valve and air switching valve and cranked engine and it ran for a few seconds each time but stalled out. Couldn't give it any throttle, either.
I can hear the fuel pump working (and it's only couple days old).
You guys are a great help and any ideas you could give me I would be most grateful.
Thank you,
Steve
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
If the pump you replaced was severely corroded (rust?) .....could you have sucked this into the line so it is now blocking the fuel filter??
Perhaps work backward. Disconnect the fuel line to the rail and have someone crank the car and see if your getting fuel. No fuel the go back to the next stop....fuel filter. Disconnect the filter and see if your fuel is flowing out the back side of the filter. If minimal, then take the line off the front of the filter....just normal siphon from the tank should have fuel running down your arms and onto the floor at this point.
OH.....don't smoke and have anything that could make a spark when your doing this...
Perhaps work backward. Disconnect the fuel line to the rail and have someone crank the car and see if your getting fuel. No fuel the go back to the next stop....fuel filter. Disconnect the filter and see if your fuel is flowing out the back side of the filter. If minimal, then take the line off the front of the filter....just normal siphon from the tank should have fuel running down your arms and onto the floor at this point.
OH.....don't smoke and have anything that could make a spark when your doing this...
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Definitely replace the fuel filter. It's not a fun job, but if the filter is clogged up, that explains no fuel at the rail. It can't hurt to let gas drain from the tank once you have the filter off. Any corrosion particles from the fuel line or from the old pump should drain out.
Just make sure to catch the old gas and do this away from any spark or flame (not near a water heater, furnace, etc.) Get the car out of the garage out in the open air.
Just make sure to catch the old gas and do this away from any spark or flame (not near a water heater, furnace, etc.) Get the car out of the garage out in the open air.
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Definitely replace the fuel filter. It's not a fun job, but if the filter is clogged up, that explains no fuel at the rail. It can't hurt to let gas drain from the tank once you have the filter off. Any corrosion particles from the fuel line or from the old pump should drain out.
Just make sure to catch the old gas and do this away from any spark or flame (not near a water heater, furnace, etc.) Get the car out of the garage out in the open air.
Just make sure to catch the old gas and do this away from any spark or flame (not near a water heater, furnace, etc.) Get the car out of the garage out in the open air.
but if you take it off before the filter and the return line then release it from the top fish it out then replace the filter will save you a few new words
