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truck won't start

3K views 17 replies 6 participants last post by  Portmanblaze91 
#1 ·
I have a 95 silverado tbi 5.7L, my question is where do the 2 lines on the back of the carb go. I believe the one on the drivers is the inlet and comes from the fuel tank throught the filter then to the carb. where does the other line go? I had to move the lines around to get my carb back on and I was curious where that one line went, and if I messed something up because the truck won't start now. Just trying to narrow things down, I just installed a fuel gauge on the the inlet line, but don't know what the other line does.........

I just put in a new IAC valve and a new fuel pressure gauge and now my truck won't start. I can see gas dripping from one of the injectors on the tbi, but it won't start. I just cranks and it has never done that........any ideas?
 
#3 ·
I agree with jepics- check your electrical connections- starting from the most basic stuff on up... keep us posted, and hang in there!
 
#6 ·
What does the return line do? by moving the return line around to get it to fit into the carb, is it possible I did something to it to make the truck not start. I know it's probably a stupid question, but I'm running out of ideas. I have ground effects on the truck, so I can't see where it goes to underneath. It's outside still surrounded by snow..........
 
#8 ·
OK, b/c you asked I'll post a 101 in throttle body (fuel) injected (TBI). Maybe understanding how the system works will help in your troubleshooting.

The fuel pump in your tank will maintain a constant pressure no matter what the engine RPM's are. The two fuel injectors in your throttle body (TB) will only take as much fuel as the computer tells them too based on throttle postion and other readings. So, since there is a constant pressure going to the TB, what fuel is not used goes back to the tank via the return line. Both lines run down the back of the engine and down the frame to the fuel tank sending unit.

If the truck has sat for a while, it may be worth it to get a rebuild kit and replace all of the O-rings. It's easy and cheap.

How did you plumb the fuel pressure gauge into the system? It sounds like your fuel is passing right through the TB. Double check your connections. making sure you didn't leave anything out or cross the tubes. The TB is marked "In" and "Out".

You have the eys on this one. All I can do is throw ideas at you.

Good luck!
 
#11 ·
the fuel gauge has a cool adapter that screws into the inlet of the tb. then the gauge screws into that. The inlet line screws right into the new adapter and I checked, there is nothing blocking the flow. I got my parts from a site called CFM technologies..........
 
#13 ·
finally got the truck started, with a new iac valve fuel pressure regulator and a new fuel pressure gauge. It seemed like I had no problems with my fuel, so I was going to try and check for spark. When I removed the first plug it was completly black, so there was going to be no spark. I picked up another set of the accel shorty plugs, spent an hour or so getting them in and it fired right up no problem. My fuel pressure was close to 15psi, so I cranked it down to 13. I will probably go lower in hopes of passing my emissions test in april. I took it for a ride to reset the computer and it did fine. I didn't stomp on, just took it up to 60. Now for the problems, when removing the two injectors there were 2 orings that held it in place. I noticed the one injector was dripping, so I removed it hoping to fix the problem. Both orings were bad, bad advanced auto only had the small one, so I had no choice but to put it back together and hope it would hold. Well it didn't, it is puddling up at the top of the injector pod and I'm afraid it might short something out? I going to have to find a replacement o ring somewhere without paying for a whole kit. Problem 2, I have this pretty loud whine coming from under the hood somewhere, it's too dark to figure out where, but I never had that before. It almost sounds like it's coming out my speakers too. Problem 3, as I'm driving I noticed my batt. gauge almost at 9 volts and it didn't move up till I took it around the corner and gave it some good pedal and it went back to 14v. Not sure where to look for that one, can anyone tell me if it is tied into the ignition coil? I switched out the accel coil with a msd I had on it before, except I never removed the accel, I just plugged it in and sat it next to the accel..........Anyway I really appreciate everyones input and patience with me, I don't think I would have got it started without everyones help, so thanks..........
 
#14 ·
HAHA! Great news. Glad to hear you fixed it, for the most part, at least. As far as problem number one, if you've got a good hardware store nearby, they should carry the o-ring size you need. That's all the help I can give... keep going, man!
 
#16 ·
Ahh yes the old fix one thing and another parts fails routine. I know this alllll too well. Hang in there. We'll get your truck up and running as quickly as you can turn a wrench!

1. Trust me pony up for the throttle body kit, it may only be about $20-$30. It comes with all of the replacement o-rings, gaskets, and screens for the assebley and injectors. The engine will run alot smoother as well. The wires are fine unless the coating has worn off or has cracked. The coating is for use in a conbustable area and the top of the injectors are sealed.

2. Remove the old coil and make sure you have a good ground with the new one. May be causing feed back in your speakers.

3. Like morganw said, take the alternator off and have it bench tested at any auto parts store. They will be able to tell you if it's working properly.
- But before that I would:
put a long metal object (screw driver) on the alternator housing and place your ear on the other end and listen for the wining.
- Then if you have a voit meter, put the positive lead on the out put post of the alternator while it is running to check the out put voltage. Does the battery gauge bounce at all?

With out seeing or hearing your truck, I am assuming that the bearings in the alternator are shot causing a wining noise and posible a voltage drop, may be even a belt squeal because it is seazing up. While your at it, pull you belt off and look for cracks or burns.

Good luck!
 
#17 ·
the other day before I seen the leak I started the truck with no whine, so I'm not sure what that was about. It may come back again once I get the truck running. I switched the accel coil with the msd I used to have on it. I think it fired up a lot faster with the msd. I'm out of work and out of money, I only started this project cuz the truck started to surge and then one thing led to another. I have an e-check in april and I need to make sure it passes, and since it was running way too rich it would have never passed, so the new plugs and gauge were very much needed. I rebuilt the carb with a kit in the summer, but cheaped out on new orings and screens. I found the orings for $3 plus shipping on line and I have to hope they work and stop the leak. Belt is in good shape only a couple of years old, it was replaced when I put a set of underdrive pulleys on with an dual electric fan. Over $200 for this 240amp alternator, so I shouldn't have problems, but I will check it out anyway. Thank you for all your suggestions
 
#18 ·
Ok, maybe someone else can help me out on this one, but would changing the fuel PSI make any difference other than loss of fuel on a TBI? I thought injectors operated at a preset pressure and will push as much fuel as the ECM calls for regardless of the amount of pressure supplied. I would be more concered that you would cause the fuel pump to fail because it is a positive displacment pump (what goes in must go out....somewhere.) hence the return line. By restricting the flow you may cause pump failure.

Someone please correct me if I'm wrong, but I think that turing down the fuel pressure is only going to cause problems and not help with emissions. I'm all ears to learn!

Try spraying carb cleaner around the base of the TB to see if the engine hesitates indicating an air leak causing false readings.
 
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