Anyone have an alldata subscription?

[boomerang]

1989 Oldsmobile Delta 88 w/3.8L code C.

I just replaced the fuel pressure regulator due to a hard start condition and the pressure seems way too low on the replacement. The car starts and runs well and a scan tool shows nothing out of the ordinary. The pressure would not increase with the vacuum line removed on the old one. The new one responds correctly in this regard but the pressure seems way too low to me.

Is this information available anywhere out there on the web? I've been searching for an hour or more and can't come up with the spec.

I've remembered why I gave up working on cars more than a decade ago. I much prefer computers.

I used to have access to alldata information when I was working, but I'm retired now.

 

[Zenmervolt]

Googling around suggests that the 3.8 should have between 28 and 36 PSI of fuel pressure.

ZV

 

[boomerang]

Originally posted by: Zenmervolt
Googling around suggests that the 3.8 should have between 28 and 36 PSI of fuel pressure.

ZV

Do you remember where you found it? I wasn't kidding, I looked for an hour. Forums?

That figure sounds right. I had 29 on the old regulator and 20 on the new. Got a bad part and bought it online too. Big hassle to return. I'm surprised it's running at that pressure.

PITA

Thanks for you help!

 

[brblx]

20 seems pretty low. what happens when you remove the vacuum source on the new one? i would expect to see an increase to the 30-40psi range.

are you sure the diaphragm on the new regulator isn't defective? any fuel coming through the vac port? do the lines hold residual pressure once the engine is turned off?

most fuel injection can actually run down to about 7-10psi, but it's going to starve at higher rpm's and probably set a fuel trim code. 20psi is unlikely to cause an issue, but something is still definately not right.

 

[Zenmervolt]

Link.

I just googled "Olds 3.8 fuel pressure" and it was #3 in the results. I'm assuming that the 3.8 was fairly similar across the board so even if the numbers there aren't precisely spot-on, they should give you the right ballpark.

ZV

 

[boomerang]

Originally posted by: brblx
20 seems pretty low. what happens when you remove the vacuum source on the new one? i would expect to see an increase to the 30-40psi range.

are you sure the diaphragm on the new regulator isn't defective? any fuel coming through the vac port? do the lines hold residual pressure once the engine is turned off?

most fuel injection can actually run down to about 7-10psi, but it's going to starve at higher rpm's and probably set a fuel trim code. 20psi is unlikely to cause an issue, but something is still definitely not right.

My recollection is that the pressure should increase 5 to 7 lbs. with the vacuum line disconnected. It does that.

The original complaint was an intermittent hard start. I hooked up the FP gage and had 29 while running. Disconnecting the vacuum line resulted in no increase in pressure. After turning the motor off the system held pressure for over ten minutes and then started to slowly bleed off. I released pressure in the system and it took 4 key cycles to bring the pressure up to 29. based upon the key cycles and the vacuum situation, I decided to replace the regulator. Just based on the vacuum situation the regulator was bad IMO.

I did not have time to do any more diagnosis with the replacement regulator. She needed to get to work. We did take a short test drive and she said it seemed to be running as it was before. I had my ancient scan tool connected and saw nothing out of the ordinary. But it was a short drive.

Just based on before and after fuel pressures, I would say the replacement regulator is defective.

I'm open to any thoughts though. It's obviously an old car and it has 175,000 on it.

 

[boomerang]

Originally posted by: Zenmervolt
Link.

I just googled "Olds 3.8 fuel pressure" and it was #3 in the results. I'm assuming that the 3.8 was fairly similar across the board so even if the numbers there aren't precisely spot-on, they should give you the right ballpark.

ZV

I fail at the googling I guess. I was not as concise with my searches.