940 fuel pressure spec

mschultz373 · 11-25-2020, 10:43 PM

what's the spec for a 94 940 Turbo? running LH2.4. I hooked my gauge up at the rail and it read ~45psi. seemed to hold for a few minutes after turning off, too. It was a quick read before leaving the shop for the night.

I read on some 'volvo answers' site that that's high, but I figured I'd come to the experts and ask.

I have yet to test pressure at the fuel supply line to the main pump. should that spec be the same?

what does it mean if my PSI is above/below the spec? I've been getting terrible gas mileage (14-16mpg) so I wonder if she's running rich, but I don't know for sure if that'd be verified with a pressure reading or not.

thanks as always yall

90volvo · 11-25-2020, 10:52 PM

I believe thats right on? But Im sure some experts will tune in .

2manyturbos · 11-26-2020, 01:11 AM

It should read 45 PSI with the vacuum line disconnected. With the vacuum line connected at idle the gage should read ~ 39 PSI.

mschultz373 · 11-26-2020, 02:53 AM

vac line at the FPR? I had that connected. so... does that mean my FPR is broken?

2manyturbos · 11-26-2020, 03:12 AM

Was the engine running when you took the reading?

mschultz373 · 11-26-2020, 03:52 AM

Yea, engine @ idle in P.

I'll take more thorough, careful readings at both the rail and supply line in the morning to confirm this finding.

2manyturbos · 11-26-2020, 04:48 AM

That isn’t that far off. I’ve seen that much variation before without problems. Measure the pressure again with the engine idling and the vacuum line off and plugged.

OttoB · 11-26-2020, 10:12 AM

My engine was running quite normal with 70 psi fuel pressure. Idle was too fat but surprisingly lambda correct the afr quite well.

mschultz373 · 11-26-2020, 02:36 PM

i think everythings fine. reading this morning was ~41psi @ idle in P with vac line attached, went up to ~50psi without vacuum. held the 41psi for 20+min after turning car off. I couldn't get a read at the valve before the main fuel pump - connected the gauge but it read 0 - but I suspect that valve may be clogged or something. the car has been running mostly fine, in D at idle it can feel rough and vibrate a lot but i think my motor mounts are completely toast.

2manyturbos · 11-26-2020, 03:22 PM

It's fine. I usually see 41-42 PSI at idle with the vacuum line connected. 45 with it disconnected.

11-25-2020, 10:43 PM	#1
mschultz373 Board Member Join Date: Mar 2020 Location: dirty coast	fuel pressure spec what's the spec for a 94 940 Turbo? running LH2.4. I hooked my gauge up at the rail and it read ~45psi. seemed to hold for a few minutes after turning off, too. It was a quick read before leaving the shop for the night. I read on some 'volvo answers' site that that's high, but I figured I'd come to the experts and ask. I have yet to test pressure at the fuel supply line to the main pump. should that spec be the same? what does it mean if my PSI is above/below the spec? I've been getting terrible gas mileage (14-16mpg) so I wonder if she's running rich, but I don't know for sure if that'd be verified with a pressure reading or not. thanks as always yall

11-25-2020, 10:52 PM	#2
90volvo Board Member Join Date: May 2017 Location: Eldorado Springs Mo.	I believe thats right on? But Im sure some experts will tune in . __________________ 90 Volvo 240-my current setup. B230ft rebuilt -8.8 comp. -Stage 3 rsi cam 3 inch ex.-GTX3076r turbo ballbearing. ebay intercooler-3 inch IC piping- Oil cooler with 10an hose. port stock intake (weak, having a custom intake by viking fab.) Megasquirt 2-1300cc injectors (running E85) 530 head with big valves ported and assemble by culberro sons car- 93 240-15g turbo-chipped-95,000 miles. Slick car Leave feedback- http://forums.turbobricks.com/showthread.php?t=355413

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11-26-2020, 01:11 AM	#3
2manyturbos Moderator Join Date: Mar 2003 Location: Monroe, OR USA	It should read 45 PSI with the vacuum line disconnected. With the vacuum line connected at idle the gage should read ~ 39 PSI.

11-26-2020, 02:53 AM	#4
mschultz373 Board Member Join Date: Mar 2020 Location: dirty coast	vac line at the FPR? I had that connected. so... does that mean my FPR is broken?

11-26-2020, 03:12 AM	#5
2manyturbos Moderator Join Date: Mar 2003 Location: Monroe, OR USA	Was the engine running when you took the reading?

11-26-2020, 03:52 AM	#6
mschultz373 Board Member Join Date: Mar 2020 Location: dirty coast	Yea, engine @ idle in P. I'll take more thorough, careful readings at both the rail and supply line in the morning to confirm this finding.

11-26-2020, 04:48 AM	#7
2manyturbos Moderator Join Date: Mar 2003 Location: Monroe, OR USA	That isn’t that far off. I’ve seen that much variation before without problems. Measure the pressure again with the engine idling and the vacuum line off and plugged.

11-26-2020, 10:12 AM	#8
OttoB Board Member Join Date: Aug 2006 Location: E(Seattle!Vancouver! San Francisco!LA!) Helsinski	My engine was running quite normal with 70 psi fuel pressure. Idle was too fat but surprisingly lambda correct the afr quite well.

11-26-2020, 02:36 PM	#9
mschultz373 Board Member Join Date: Mar 2020 Location: dirty coast	i think everythings fine. reading this morning was ~41psi @ idle in P with vac line attached, went up to ~50psi without vacuum. held the 41psi for 20+min after turning car off. I couldn't get a read at the valve before the main fuel pump - connected the gauge but it read 0 - but I suspect that valve may be clogged or something. the car has been running mostly fine, in D at idle it can feel rough and vibrate a lot but i think my motor mounts are completely toast.

11-26-2020, 03:22 PM	#10
2manyturbos Moderator Join Date: Mar 2003 Location: Monroe, OR USA	It's fine. I usually see 41-42 PSI at idle with the vacuum line connected. 45 with it disconnected.