90 with no fuel pressure.
Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
90 with no fuel pressure.
Hi all,
I've hit a wall and run out of ideas on how to troubleshoot this issue further. The car is a 90 L98 and has been sitting without running for about 2 years. Charged the battery up and it is cranking fine but not starting.
Hooked up the fuel pressure gauge and am getting 0psi. What I've checked/replaced so far:
1. Replaced fuel filter. I had a nice gasoline shower so the lines were full of fuel.
2. Getting 12v at the pump for 3 seconds in Run and full time when cranking.
3. Replaced fuel pump. New pump does away with the pulsator and replaces it with a hose and clamps.
4. There is fuel at the test port on the rail, just no pressure. If I press the valve core I get a little fuel flow for a bit but no spray like I would expect.
5. Clamped off the return line at the tank while cranking and no improvement (Still 0 psi).
Tomorrow, I'm going to try hooking up an ammeter to see if maybe I'm not getting full power (odd problem but seen it before). Also going to try running the pump off another power source for the same reason.
Other ideas? I'm missing something - what else would cause a no start and no pressure?
Thanks!
I've hit a wall and run out of ideas on how to troubleshoot this issue further. The car is a 90 L98 and has been sitting without running for about 2 years. Charged the battery up and it is cranking fine but not starting.
Hooked up the fuel pressure gauge and am getting 0psi. What I've checked/replaced so far:
1. Replaced fuel filter. I had a nice gasoline shower so the lines were full of fuel.
2. Getting 12v at the pump for 3 seconds in Run and full time when cranking.
3. Replaced fuel pump. New pump does away with the pulsator and replaces it with a hose and clamps.
4. There is fuel at the test port on the rail, just no pressure. If I press the valve core I get a little fuel flow for a bit but no spray like I would expect.
5. Clamped off the return line at the tank while cranking and no improvement (Still 0 psi).
Tomorrow, I'm going to try hooking up an ammeter to see if maybe I'm not getting full power (odd problem but seen it before). Also going to try running the pump off another power source for the same reason.
Other ideas? I'm missing something - what else would cause a no start and no pressure?
Thanks!
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Well u should still pull the codes. I dont know how many owners start troubleshooting and dont bother to look for DTC codes. All it takes a jumper wire/paper clip. But i think u know the problem - no fuel press.
Yea zero fuel press is a show stopper. U can back pin connectors with sharp probes on the VOM leads to check for power and voltage. BTW a DC ameter is pretty expensive. Make sure your reading the VOM correctly by measuring the battery voltage.
Something that may be throwing u off is when u measure voltage accross a pump winding with very low resistance u may not get a full battery voltage reading, voltage drop as the wiring and connectors in series will have enough resistance to drop significant voltage. And a lot of hobbyists get fooled by measuring 0 volts across closed contacts and connectors as it will measure near zero volts. U measure voltage to batt negative to check for power on the circuit but measuring across closed contacts will be near zero even though it is 12v above batt negative.
Something else is the newer quick connect fuel line connections can fool u they are not seated/sealing. More so at the fuel filter. Look for fuel on the ground under the car. Had my camaro towed once when i found fuel pooling under the car and afraid for my garage and home.
Hope this can help.
Yea zero fuel press is a show stopper. U can back pin connectors with sharp probes on the VOM leads to check for power and voltage. BTW a DC ameter is pretty expensive. Make sure your reading the VOM correctly by measuring the battery voltage.
Something that may be throwing u off is when u measure voltage accross a pump winding with very low resistance u may not get a full battery voltage reading, voltage drop as the wiring and connectors in series will have enough resistance to drop significant voltage. And a lot of hobbyists get fooled by measuring 0 volts across closed contacts and connectors as it will measure near zero volts. U measure voltage to batt negative to check for power on the circuit but measuring across closed contacts will be near zero even though it is 12v above batt negative.
Something else is the newer quick connect fuel line connections can fool u they are not seated/sealing. More so at the fuel filter. Look for fuel on the ground under the car. Had my camaro towed once when i found fuel pooling under the car and afraid for my garage and home.
Hope this can help.
Thread Starter
Le Mans Master
Joined: Apr 2002
Posts: 5,726
Likes: 46
From: Waukesha WI
St. Jude Donor '15
It's ALIVE!
When I hooked up an external power source to the connector outside the tank, I noticed that the pump didn't want to run consistently so I started looking at the in-tank wiring. It appears there was some light corrosion on the terminals. A little sandpaper to clean them up and she's good to go.
Also found that the fuel pressure gauge I was using doesn't work very well. It only shows pressure when it wants to making troubleshooting a heck of a lot more difficult. Unless my magical engine can run on 0psi of pressure for 10 minutes w/o a stumble.
Thanks all!
When I hooked up an external power source to the connector outside the tank, I noticed that the pump didn't want to run consistently so I started looking at the in-tank wiring. It appears there was some light corrosion on the terminals. A little sandpaper to clean them up and she's good to go.
Also found that the fuel pressure gauge I was using doesn't work very well. It only shows pressure when it wants to making troubleshooting a heck of a lot more difficult. Unless my magical engine can run on 0psi of pressure for 10 minutes w/o a stumble.
Thanks all!
