SwedeSpeed - Volvo Performance Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
853 Posts
Discussion Starter · #1 ·
The car has 135 thou on it. Fuel filter was replaced 30 K ago. The car has a plastic tank. If I drive it for a while and then shut it off for 15 minutes or so it sometimes stumbles on restart especially when it's hot outside. It will start normally if I energize the pump and hear it shut off before I crank it On a cold start the pump runs about 4 seconds for the fuel pressure to stabilize at 44 psi with a gauge connected to the rail. It starts perfectly. Question is how long should the system hold that 44psi and what should it drop off to after about 2 hrs. of sitting. If I energize the pump every time even when it's hot, it also starts right up.
Could the issue be caused by the check valve in the pump leaking back the pressure? And is this a sign of the pump beginning to fail? There is no info in Vida about fuel pressure drop off. Anyone have an opinion on it?
 

·
Registered
Joined
·
306 Posts
Per VIDA "The line pressure must not fall below 200 kPa within 20 minutes of the fuel pump (FP) being shut-off."

In Vida go to:
>Fault Tracing
>>Symptom Related Diagnostic procedures
>>>Engine With mountings and equipment
>>>>Ignition and Control systems
>>>>>Control System Fuel Supply
>>>>>>Checking fuel and residual pressures

Once your there Click continue, Then click YES for information on checking REST PRESSURE. 200 kpa is roughly 29psi.

Hope this helps.
 

·
Registered
Joined
·
853 Posts
Discussion Starter · #3 ·
Thanks a lot Importservice. I will now hook up my Vida laptop to check it out. I did look in Vida but not hooked up to the car. Now I know bettter.
 

·
Registered
Joined
·
16,855 Posts
Agreed. I graphed the pressure to know for sure what the deal was. It was like a Richter scale.
It's all good buddy. Sometimes ya just gotta dig around in Vida and you'll find stuff you never knew was there..



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
853 Posts
Discussion Starter · #6 ·
Well guys thanks 1st. I did the Vida scan. No codes, and the scan, all 3 lines were flat. Tried seeing if they would change with rpm. They did not. Also let Vida check for faults in the ECM and CEM. Again no faults found. But with a known good mechanical gauge, key on and primed up, I get 44 psi. Engine running at idle and 2400 I also get 44psi and it bounces slightly but stays up around 44. No miss fires at all. Runs really nice and smooth. No issues under boost either. BUT! the prime up time is excessive after cooling down, about 5 seconds until the pump rests. After sitting overnight or several hours,resting pressure drops to Zero psi. Then if I energize the system, it will start right up and sometimes I will have to crank it again and then it runs smoothly.My only GUESS at this point is that the pressure return check valve in the pump bleeds off pressure as indicated by the gauge.It is my understanding that it should rest at 29psi and stay there. Right or wrong? So I ordered a pump,big O ring seal, and tool to replace the whole thing. Before I post this, I tried my best to see if there is a injector leak. There are no indications of that thank goodness. So far pulled the back seat and stuff. PIA for sure. And found evidence of mice on top of the pump and harness connections. They chewed the tape but luckily didn't get to the wires yet. Mothballs will go on top the FP cover plate before the back seat goes in for sure. Well, long post. Crapshoot diagnosis and I hate that. But at 136 thou and found the mice thing, I guess it isn't the worst thing. We shall see. Please comment if inclined to do so. Thanks for reading.
 

·
Registered
Joined
·
306 Posts
Put a pump in it :)

If there was an injector leak, you would gets misfires on start up most of the time. Usually you would be able to pull plugs and get some type of indication by looking at the dirty plug to see which cylinder would a likely culprit.
 

·
Registered
Joined
·
853 Posts
Discussion Starter · #8 ·
Put a pump in it :)

If there was an injector leak, you would gets misfires on start up most of the time. Usually you would be able to pull plugs and get some type of indication by looking at the dirty plug to see which cylinder would a likely culprit.
That is was I will do. Replace the pump. And Tool to release the plastic ring and Bosch pump with original O ring seal is coming to me in the next 2 days.Parts from FCP. All cleaned up and ready to pull original pump. I want to check for leakage around the area before putting back the rear seat. Could there be an issue with the air bags if I leave the connector unpluged and leave the seat out while I can monitor for a leak? Thanks IS. You are on it. And I appreciate your answers a lot. BTW,I did see evidence of mice chewing around the area on top of the fuel pump cap. I closely looked and don't see where they might have actually gotten past the insulation on each wire. I think I got ahead of that nightmare. That harness has all the clues to cost big $$$.
 

·
Registered
Joined
·
306 Posts
As far as the mice, yeah it happens, we've seen them chew through Rear harnesses and short out REM's lol. Of course the woman they did that too probably deserved it ;). If you see any damaged wires, just repair them. Even it they chewed through a wire, that wouldn't have any bearing on you losing fuel pressure after the vehicle is shut off.
 
1 - 9 of 9 Posts
Top