HELP: Fuel pressure issues

[tt455]

I know this has been talked about often but I still need advise. I posted three videos so maybe if other people have this problem it will help them also.
I have a video of my numbers and then pressure with key on and then running at start up. At start up she did finally shut down it's a little noisy but does quiet down later.
With key on I was only at 20psi but after rapping on filter and regulator I got more like 30, but drops quickly as seen. At start up it's steady at 40+ but almost sounds like it's starving for fuel? If I feather the throttle it will eventually run but does stutter irregularly and stall. I'm thinking first changing the fuel filter and then possibly checking or replacing regulator, pump relay? Or is there a leak down? I'm not sure but this is the usual things that I read about in the threads.
This is what I know of the build which was done by previous owner.
87 Turbo T WE4
rebuilt about 5k on engine
206/210 roller cam
roller rockers lifters
arp studs 20 over
crank rods 10 under
rjc pullies
ken bell air dam and intake
340 fuel pump hot wire
new sending unit
Art Carr built trans
3" single exhaust

 

['87 Turbo "T"]

Split supply hose on pump in tank?

 

[tt455]

Split supply hose on pump in tank?

I don't know, I'll try and check the hose tomorrow.

 

[js402]

Sounds like you're losing pressure at the pump to me.seeing as it was done by previous owner who knows how long ago, I'd just swap the pump, lines and reg and be done w the issue 525, lines , and a good adjustable reg will solve it.

 

[tt455]

Sounds like you're losing pressure at the pump to me.seeing as it was done by previous owner who knows how long ago, I'd just swap the pump, lines and reg and be done w the issue 525, lines , and a good adjustable reg will solve it.

The gauge stays steady at 40psi even when about to stall, would that still happen if pump was losing pressure?

 

[Chuck Leeper]

The gauge stays steady at 40psi even when about to stall, would that still happen if pump was losing pressure?

May hold psi while the volume required is low.
What did I see with batt volts when idling?

 

[mblum]

I wouldn't worry about the fuel pressure at the rial with the engine off. All of the Racetronix pumps/sending units I have had seem to bleed off pressure just like what you showed in your video once the key is off. They have never given me an issue while running so I don't worry about it.

A few things:
-I wouldn't trust those rail mounted fuel pressure gauges too much, mine will read 4 psi different depending on engine bay temperature. A high quality gauge with a hose long enough to get out of the engine bay and/or a fuel pressure transducer that can be used to log fuel pressure have given me the fuel pressure info I use when tuning, the rail mounted gauge is what I started with but in the future I will not be mounting one. My rail mounted gauge is now purely cosmetic at this point.

-The fuel system..... on these cars is so critical, being a previous owner did the work and your chasing some issues i would consider going through the whole fuel system to confirm that it's up to snuff. That includes inspecting the tank, sending unit, all the hoses on the sending unit, the wiring and grounds, for the fuel pump/hotwire setup. The fuel lines including the fuel filter (just replace it).

-What fuel injectors are in the car? Age of them? Have they been cleaned and flowed to confirm they all flow the correct amount of fuel and flow equally? If they do not flow the specific amount of fuel that the chip in the ECU has been setup for, you will be on the struggle bus forever.

-What chip is in the ECU?

-What Mass Air Flow sensor is on the car? OEM or upgraded with a modern unit and translator?

-O2 sensor condition? If unknown they are cheap and easy to replace. If they are not functioning correctly they car will never run well.

-In your first video I saw the BLM's at 138, which indicates a possible vacuum or exhaust leak (before the turbo) and those leaks will cause issues as well. I would confirm your O2 sensor is functioning and fuel issues are resolved first as they can cause the BLM's to be be high as well.

 

[tt455]

I wouldn't worry about the fuel pressure at the rial with the engine off. All of the Racetronix pumps/sending units I have had seem to bleed off pressure just like what you showed in your video once the key is off. They have never given me an issue while running so I don't worry about it.

A few things:
-I wouldn't trust those rail mounted fuel pressure gauges too much, mine will read 4 psi different depending on engine bay temperature. A high quality gauge with a hose long enough to get out of the engine bay and/or a fuel pressure transducer that can be used to log fuel pressure have given me the fuel pressure info I use when tuning, the rail mounted gauge is what I started with but in the future I will not be mounting one. My rail mounted gauge is now purely cosmetic at this point.

-The fuel system..... on these cars is so critical, being a previous owner did the work and your chasing some issues i would consider going through the whole fuel system to confirm that it's up to snuff. That includes inspecting the tank, sending unit, all the hoses on the sending unit, the wiring and grounds, for the fuel pump/hotwire setup. The fuel lines including the fuel filter (just replace it).

-What fuel injectors are in the car? Age of them? Have they been cleaned and flowed to confirm they all flow the correct amount of fuel and flow equally? If they do not flow the specific amount of fuel that the chip in the ECU has been setup for, you will be on the struggle bus forever.

-What chip is in the ECU?

-What Mass Air Flow sensor is on the car? OEM or upgraded with a modern unit and translator?

-O2 sensor condition? If unknown they are cheap and easy to replace. If they are not functioning correctly they car will never run well.

-In your first video I saw the BLM's at 138, which indicates a possible vacuum or exhaust leak (before the turbo) and those leaks will cause issues as well. I would confirm your O2 sensor is functioning and fuel issues are resolved first as they can cause the BLM's to be be high as well.

Thanks so much for taking time out to reply.
The key was on the whole time when the pressure was dropping.
I don't know what injectors or chip I'm trying to get in touch with the mechanic that took care of this car before I purchased.
I'm not getting any codes form o2 and maf, it does have ken bell air dam, but will look.
So those reading on scan master was when the car was warm and seemed to run fine but then after idling 5 minutes she started to stumble and stall.
I was thinking and looking for a vacuum leak also, no luck yet.

 

[tt455]

Split supply hose on pump in tank?

Well a spit but looks like on the return line. I don't see any leaks but need to replace. I don't think this would cause my issues?

 

[tt455]

OK so this morning I started the car idled around 900rpm then stalled. Second try idle raced for a minute and then sputtered and backfired died. Both cases with no throttle pressing.

 

['87 Turbo "T"]

Well a spit but looks like on the return line. I don't see any leaks but need to replace. I don't think this would cause my issues?

Can't hurt to replace.

I meant the hose that feeds from the pump to the sending unit inside the tank.

 

[XracerX]

With key on I was only at 20psi but after rapping on filter and regulator I got more like 30

Change your fuel filter FIRST ! The fuel pump only runs for 3 seconds with the key on and car not started.
A faulty fuel pump relay could cause this too especially and more so if the hot wire kit has the relay mounted under the rear bumper.
As far as the fuel pressure bleeding down that could be a stuck open injector or bleed back through the regulator.

 

[tt455]

Ok thank you, I will do that first. Yea it is under rear bumper.

 

[tt455]

Change your fuel filter FIRST ! The fuel pump only runs for 3 seconds with the key on and car not started.
A faulty fuel pump relay could cause this too especially and more so if the hot wire kit has the relay mounted under the rear bumper.
As far as the fuel pressure bleeding down that could be a stuck open injector or bleed back through the regulator.

So I changed out the filter and it seems to have helped. She started but the rpm’s were high around 2200 and didn’t come down. I shut it down and on second start it started to run fine with a lower rpm. I’m thinking I have to adjust the tps again. A rain storm came through so I didn’t have a chance to do it. Will update as soon as I can.
Another quick question, before this I pulled and cleaned the plugs. On the above mentioned build previous owner was running the current AC plugs r45ts with a .22 gap. I feel this should be around .30? Thanks for your help.

 

[mblum]

Plugs gapped at .022" are fine. Going too wide quickly increases the chances of blow out the spark at peak boost. My stock ignition will blow the spark out with plugs gapped at .030" at around 20psi. If I gap them down to .022" to .024" I no longer will have the spark blow out issue.

As far as cleaning plugs, I would just replace them. They are cheap enough.

 

[XracerX]

On the above mentioned build previous owner was running the current AC plugs r45ts with a .22 gap. I feel this should be around .30?

R45TS plugs is one heat range higher than stock. Stock is R44TS for low boost levels no higher than 14psi.
You should be going with a colder plugs like the AC R43TS gapped @ .032-.030 not 2 ranges higher.

 

[tt455]

So tps was fine today but still have the same issues even after changing filter and relay.

 

[Chuck Leeper]

I see no reference to data logging.
Videos are useless when doing this type of T/S.
Spending big cash on the build should include a data log system.

 

[tt455]

I see no reference to data logging.
Videos are useless when doing this type of T/S.
Spending big cash on the build should include a data log system.

I guess you didn't read the whole thread, but thanks anyway.

 

[Chuck Leeper]

I guess you didn't read the whole thread, but thanks anyway.

I saw a scroll thru a SM.....
Hardly a saved/reviewable log.
But thanks anyway for reminding me.