Chrisry1995

iTrader: (1)

Having a problem with engine not starting when cold. Will fire-up if spray fuel in thottle body. 89 305TPI Trans-Am. Put guage on and Pressure will go to 38 psi when turn key, but then it drops pretty fast when sitting. After car starts, 42 psi and 50 psi when disconnect vacum to fpr. Now if I clamp off the return hose, the pressure will stay up. So I changed the diaphram. Still not holding. Also engine seems to miss after warms up when under load. New plugs,wires,cap rotor, ign.moduel,fuel filter, fuel regulator kit. Presure gauge is on fuel rail, so can't tell what it's doing when driving. Also the no start thing is intermitant. sometimes it starts right up. Other times it takes a few cranks. Then some times won't start without start fluid. It tries to start, but just can't get it.Will always start when warm. It seems that after I play with the flex fuel lines, it works good for awhile. This is why I thought the fpr would fix it. Any Ideas. Don't want to change fuel pump unless I know it's bad.

2000ws6

iTrader: (1)

When you say "drops pretty fast" are we talking seconds, minutes, hours? Should hold pressure for at least an half hour. If it holds when you pinch the line, bad pump and/or pulsator. Symptoms are exactly the same as the bad fuel pump I just replaced in my son's '89 305 TPI Trans Am. Took 5 hours to R&R the pump, start to finish, including trips to the parts store.

Chrisry1995

iTrader: (1)

I'm talking seconds. Drops from 38 to 25 in 10 seconds, then to 10 after a couple minutes. The thing I don't get is the return line will hold pressure when squeezed. So that is suppose to be the regulator. It acts the same with feed line squeezed, ruling out the pump, so the manual says. I have the full factory manual. I also don't see how that little button on the fpr is suppose to hold back the pressure. I wiped the seat with paper towel and the old button/diaphram had alittle wear. But the button sits on the seat metal to metal? The regulator regulates fine, it just seems to dump the fuel back to the tank.

2000ws6

iTrader: (1)

On the flow chart, pressure "NOT OK", "...But Less than 280kPa 40.5psi" See Chart A-7 page 2 of 2.

Have you checked the in line filter? Checked fuel lines for kinks, bends etc? IF all OK, apply 12V to the pump, slowly pinch the return line to check for pressure rise. If less than 40.5 psi it could still be the pump.

customblackbird

iTrader: (15)

hmmm sounds like u got a pump prob. how many miles on the car? i would replace it anyways its only a 160$ part for a high flow one. if u replaced the FPR and the diaphram and u didnt mess anything up it sounds like the pump and u did the filter so ur good. i would say pump or u got a leak in one of the lines at the tank. the top of the tank where the sender is there are a bunch of rubber lines that attach the fuel lines to the lines coming outa the tank, urs are no doubt original so those could be bleeding off air/pressure. i would say all the probs are at the tank.

Chrisry1995

iTrader: (1)

Replaced the in-line filter. also applied 12volts to fuel pump. I do get a very big pressure increase when pinch the line, like 60 psi. When pinch then let go, pinch, let go, the pressure goes up and down. probably will go higher, but should keep at 60 psi so diapham don't blow BTW, I hit a mile-stone today. I checked the resistance of my injectors and #1 is 2.2 ohms also they all range from 9 to 17 ohms. So I need to get that fixed first. Explains why it runs rough when warm, hard/no start, and intermitant.

2000ws6

iTrader: (1)

Sounds like you may have found the problem. Hopefully you won't have to do the fuel pump, though the injectors aren't much fun either!