T/Atime

lastnight i decided to go for a joy ride. took it out on the highway and she ran great. went down a few residential streets driving like 40km/hr for a few mins. Then the car starts to stumble NOT THE FIRST TIME THIS HAS HAPPENED i thought this problem was fixed 3years ago with my walbro fuel pump. I have a fuel pressure guage mounted on my fuel rail. i popped the hood and its almost stalling, and the fuel pressure is dropping all the way to stall. ill wait a few mins and its up at 43psi, ill let it run and she drops to 10 psi after 30seconds.

ive relpaced my afpr with a kirban
replaced the fuel filter
last year it died in the same way and i dropped it off at a local shop. they determined it was and old distributor and i decided to replace it with a msd unit/ ignition module
the car ran great for 3000km

last night was the first time in a while its acted like this.

can someone give me some insight on what the problem sounds like or what direction i can move into to solve this

John 89 Formula

Assuming the fuel pump is still good, I would start with the fuel pump relay and the oil pressure switch.

T/Atime

how do i test the relay? or know if this is my problem?

John 89 Formula

not sure how to test it, but seeing that it is probably 20 yrs old you may want to change it anyway.

T/Atime

first i have to locate this unit then ill apply 12v to it and if it closes im assuming its still good. funny thing is anything i replace it runs strong for a period of time then i almost forget about this old problem and she dies!

T/Atime

im sure its not an expensive part but theres no chattering. ill be testing it when i work on the car next. just replacing it cuz its old seems like a lazy mechanic way to do things. i call it "throwing parts at the car".

T/Atime

worked on the car a little bit today. runs perfect 43 psi for like 15min. i picked up a fuel pump relay for the hell of it.

is it possible my ignition is breaking up and cutting my fuel pump off and on, to the point where it still runs but like i said above fuel pressure drops down to a point where car stalls out?

i dont care what the problem is but its important not to replace a part thats still working. my gta is historicaly very unreliable, this car has left me stranded in some bad spots. I want to take this car on trips this summer.

Now if its the fuel pump, id like to look into making an access door in the car. I would bring a spare fuel pump with me just in case. im not afraid of dropping the tank with the exhaust..... just need it to be practical.

So can someone share there experience with me, if this sounds like something youve been though id like to hear your thoughts.

T/Atime

lastnight i drove the car to my brothers house where it died.

can someone give me ideas on this problem!!
when it acts up:

-car does not reach 43psi
-i turn the key forward to activate the fuel pump, fuel pressure stays at 10psi
-i crank the starter for 3-6seconds car fires up and pressure @aprox 30psi, right away pressure drops to stall the car within 30seconds to 1min.
-if i leave the car overnight i have no problems 43psi

what could it be?

EDGE

I wish I had an answer. I'm having the exact same problem verbatim. It happened to me yesterday for the first time. My pump has 500Km's on it. I'm reluctant to just change it out again. I'm also scared to drive it anywhere. I'm going to look at this oil pressure switch idea.

John 89 Formula

bad fpr, maybe, pull the vacuum hose off the regulator and see if any gas comes out of the nipple.

T/Atime

ive replaced my old holley afpr with a kirban last fall. also the other day i had the vacuum line pulled off and its dry.

foxmartin1

I'm having the same problems. Have we figured it put yet? Mine will run great till it hits 220 degrees and the fan kicks on and then it will hesitate and have a spark knock. But even when its cold it still only gets 20 psi in the fuel line. I've tried 4 different brand new pumps. Regulator is good, lines are good.

EDGE

Fuel filter. Mine was Plugged.

foxmartin1

My fuel filter is brand new

NY87Iroc

iTrader: (1)

when u replaced the fuel pump did u connect it to the fuel line with that short hose they give u or did u reuse that damper ( I think thats whats its called) that came from the factory? Its between the fuel pump and the hard line on the sender.

John 89 Formula

It's called a pulsator valve, it also has a rubber diaphram in it. If that is torn it can affect your fuel pressure.

foxmartin1

Short hose. My mechanical told me that sometimes the dampeners go bad and leak pressure.

foxmartin1

Is the stock fuel pressure regulator adjustable? If so could the previous owner have set it wrong? And if its not and I replace it with an adjustable one would that help get the pressure up or even if I adjust it not help much?

T/Atime

this pulsator valve is to be replaced with a new one or just a high pressure hose? what is this function of this valve? im assuming constant fuel pressure. how do i test my charcoal canister btw. this might be a problem as its been in and out of the car.

T/Atime

quick update, im still not driving the car. this week i have time to spend on the car. ive decided to look into the pulsator valve, and or fuel pump. So ive made a nice clean hole to make a fuel door access. im not to sure how to remove or disassemble the old pump to remove the pulsator valve. Also im thinking of buying the ractronics 255 walbro and wiring kit for added insurance. Where is the best vendor considering im in Winnipeg, Canada. part number would be helpful too.

T/Atime

Attachment 221470
ive tryed to search but couldn't find instructions on how to remove. might just stop buy a shop tomorrow to show them what the unit looks like and they can disassemble. the pulsator looks like a minature break fluid resivour?

btw im thinking it would be silly to make an access door and not have a spare pump in the car for a quick change right?

John 89 Formula

there is really nothing to it, take the filter sock off and slide the pump up the pipe a little and lift it out. there's nothing mechanical holding it in place it basically stays there because it's kind of a tight fit.
Yeah, that little brake resevior is the pulsator.

T/Atime

perfect! ill try it tomorrow.

T/Atime

little update. ive removed the sending unit replaced the pulsator with a hose. same problem happens. ive ordered a new walbro 255.
im not concered about the labour now cuz ive made a nice clean fuel pump door.

Today i found a few members struggling with the same issue. sounds like fuel boiling might be the cause. tomorrow ill be moving my fuel lines far away from any heat sources as possible. ill even jack up the car and manipulate the pitch of the muffler and see if i can add space between the tank/ heat sheild/ muffler.

if this doesnt work ill throw in a new pump. if that doesnt work you can find me in the for sale section of this club

T/Atime

the gta runs great now!!
i decided to make a fuel pump access door. nice and clean job with tin snips and covered with a thicker guage metal plate with a gasket. First i replaced the pulsator valve with a hose put it back together. still runs like ****. next i ordered a racetronics fuel pump, walbro 255. got it in the mail today. Replaced it in 20min!!! fired it back up. usually i run my car at 43.5psi and i noticed im at 45psi now. i left it there for now took it out for a drive and its like night and day.

at idle the old pump was good for 43psi but im assuming once the fuel demand increased the pump could not keep up. i had a hard time beliving that this pump "kinda worked" didnt realize there was a grey area. im assuming these things heat up and stop working. i was even experiencing fuel boiling. i still have to check if my fuel is not vaporizing but seems to be running just fine...

fingers crossed and spare pump in trunk!