OutSource

ok thank you for the reply. I just put the new spider injector unit back in the truck "since gm said it needed a fuel pressure regulator and the one they sold me was bad" Im getting 60psi when I turn the key on but it drops to 50-55psi. The trucks still not starting after its warm so I have no idea at this point. It is losing pressure though, about 10psi and hr, but that should'nt effect it from starting if the pressure is getting to 60 even after it has dropped to zero.
I checked all the all the fuel line fittings and thier tight, so I'm not sure where its losing it from, maybe a return line is leaking. There is no way GM sold me two bad units is there?

shamrock246

maybe the check valve in the fuel pump isnt closing all the way,did the coolant temp sensor resistance check out cold and hot?


Sean

97 4x4 burb

OutSource

Thank you for the reply, I'm getting 60 psi when I turn the key on and then it drops to 55psi and it starts when it's been sitting at that pressure. The fuel pressure drops to 50-55psi when running, and the truck is losing fuel pressure when it sits about 10psi an hour? Is that normal? I would think it should hold fuel pressure over night. I recheck all the fuel line fittings and their tight, I would think it should hold fuel pressure overnight. Even though it's not holding pressure overnight it still starts fine and shouldn't casue it to not start once its warmed up, although it is loaded with fuel onces it's been started.

I when back to the dealer to bring back the part they said was defective (MFI injector kit) and asked to speak with the service manager about them saying the truck was holding almost zero pressure with the key on, and the fact that they wanted 750 to replace it without the cost of the part; when it took me 3.5 hours to repalce the new injector kit. So they said they would look the truck over once again for free since they charged me to look at the truck and diagnosed it with a bad fuel pressure regulator; which didn't slove the problem.

So we'll see what they say tomorrow and I'll let everyone know what the problem was.
Replaced so far
1.MFI injector kit
2.Fuel Pump
3.Fuel sending unit(2 part system on the 2dr's fuel pump not included)
4.Serpentine belt
5.Alternator (stock 105amp)
6.Spark pulgs (.060 gap)
7. Bank 1 senor 2 O2 sensor

OutSource

Sorry Shamrock did'nt realize there was a page 2 on my tread and thought my post never when up so i didn'nt see your reply.
How do you check to see if either of those is working properly?

shamrock246

here's a link to a thread with the resistance values vs. temp ECT resistance values - HP Tuners Bulletin Board its also in the Haynes book in chapter 6 you can get that book at autozone the sensor will have 2 wires going to it and will be by the t-stat housing


Sean

97 4x4 burb

shamrock246

is the idle air control valve sticking when it gets warm,does it look like its flooded when it starts hard (black smoke out the exhaust )you could pull a couple of plugs to see if there wet,check the spark cold vs. warm maybe its it get weak with heat


Sean

97 4x4 burb

OutSource

Ok for those who may have the same problem as me, my truck is fixed. COOLANT TEMP SENSOR 34 bucks from gmc and the truck is starting normal again.

Thanks for the replys and help. IF anyone needs a new fuel pressure regulator I have a new one or would like to see picutres or a video on what the spider injector looks like under the upper intake or the location of the fuel pressure regulator the 96 5.7 350 let me know and I can add a post of the video and pictures. If you want to replace one yourself.....since gm will charge you 800 to have it replaced.
Thank you all again, Paul

73shark

Any pics/videos are always welcome.

Glad you got it fixed. Thanks for letting us know what it took.

shamrock246

thats cool!!!


Sean

97 4x4 burb

aaronk

OutSource, I just wanted to thank you for sharing your experience with your Tahoe. I have a 1996 that was doing the same thing. It happened all at once when I shut it off for about five minutes. But mine also lost its overdrive.
I read your experience with your starting problem, put in a temperature sensor and it fixed the starting problem and fixed the overdrive. Then I registered on this forum it saved me alot of grief and money. Thanks again.