96 Tahoe Stalled/Will Not Start Now

[gregsb]

I had hoped to not have to post a problem this soon but no such luck.

Today I went to take my truck out for lunch to run some errands and it started fine but when I pulled out and drove it about 100 feet it died and will not restart. I do not smell fuel when I crank it over but the relay does click when I turn on the vehicle and when I crank it.

I could not hear the pump but do not know if that is due to too much pressure in the lines or the pump failing to run (seeing as I am not smelling fuel I suspect the fuel pump is not running. The pump was replaced by one of the local Chevy dealerships last year and has about 1500 miles on it is all.

Any ideas about where to go from here? This is the first injected used truck I have ever had to troubleshoot so I am new to this (all my other trucks have been leases so I never had to worry about troubleshooting).

 

[SunlitComet]

If you turn your key to start and don not hear anything running in the back then your fuel circuit is probably not running. It should be easy to hear. You should inspect the 20amp mini fuse labeled ECM-B. It is located in the under hood fuse/relay block left side near the firewall. Its location is mark on the inside of block cover. While the pump draws power from the fuse at all times when running the fuel pump relay is only used during priming ant starting when engine is actively running and oil pressure switch power the pump from that point. Even if the repair is out of warranty time wise the dealer may be willing to cut you a break since it failed so early so I would suggest asking them for help again.

 

[ezdaar]

1st: swap in a known good relay inplace of possible bad FP relay, Turn key to on, listen for pump. Sometimes with Full tank it can be hard to hear. Have helper turn key while your near tank..
2nd: Apply 12volts to fuel pump prime wire, its located Very close to brake booster.
Aprox 6" red wire hanging loose with along rectangle black socket on the end.. Very possible it might be still tucked up inside the main Wire loom, leading to firewall connection..

If pump is good you will hear it kick on immidiatly. If you get a good electrical arc when touching the wire to positive batt post but no pump noise, more than likely the pump is shorted out aka dead..
If you dont get a arc at all and dont hear pump kick on, its dead..

Could also be a bad ground, Check frame rail near tank for 2 large black wires sttached to frame, Clean connection, try above test again..

There have been cases where the FP harnes that leads into teh tank has gone back, so check for 12 volts at plug above tank with the FP prime wire hooked to 12V, If you get 12 at plug, pull pump assembly, unplug FP and check there for 12V
If you have 12V all teh way,, Dead FP...

GL, have fun.. Dont blow yourself up..

 

[gregsb]

Thanks for the quick response.

I just checked the fuse and it is good. When I get it home I will check the circuit to see if it is getting power at all.

 

[gregsb]

Thanks for the input...

So far I have replaced the Fuel Pump relay, tried to run the pump using the bypass as mentioned, cleaned the ground connections and the truck still does not run.

I did test the harness back near the fuel tank and the 3 prong connection shows power on the center prong when I am using the primer bypass but the signal appears week ( I only had a test light last night and it had strong light at the fuse block but week/dim light at the center prong. I now have a volt meter to measure voltage tonight so I can see what it is putting out. I am considering running a wire directly from the battery to the fuel pump to see if I can get it to fire. If I do that I should put power to the grey line correct?

I went back through the records for the truck and the pump was replaced in May of last year with an ACDelco unit by the dealer and only has a little over 900 miles on it - which is less than I had guessed yesterday.

Any other ideas?

Thanks,
Greg

---------- Post added at 10:52 AM ---------- Previous post was at 10:48 AM ----------

One other question about the forum in general, when I see Jonathan (Sunlitcomet) post a diagram the one that shows is usually not the one that matches the text of the post. Am I doing something wrong? I had the wiring diagram that was posted yesterday for the fuel system showing fine until I logged off yesterday and last night I was seeing completely unrelated images.

 

[SunlitComet]

It is not you. there is a fast and simple way to post info like i did above. Unfortunately they load from a different servers than mine or this website. One of those server rotates the location of images on a regular basis. If you don't get it the first time PM me and I will redo the specific post. There is a better way but it is very time consuming and it really slows down my response time for everybody.

---------- Post added at 02:15 PM ---------- Previous post was at 02:10 PM ----------

BTW you may can expect about a 1 volt drop in the back be sure you have no scents of gas vapor around first. And yes the gray wire.

---------- Post added at 02:19 PM ---------- Previous post was at 02:15 PM ----------

look at the diagram again above. That is why I prefer the other way is much bigger. There is another solution but it has a potential glitch that may cause me some grief. I have not found a way to resolve it yet.

 

[gregsb]

Just a quick update on my Tahoe. After following everyone's suggestions here I found that I was getting full voltage to the fuel pump and nothing out. Since the fuel pump had less than 1000 miles on it I took it into the dealer that did the work and they found that the sending unit negative post had completely burned off and replaced the pump/sending unit under warranty so I wound up only paying labor and have a fully warrantied pump again.

I took it out for a test drive on Sunday and did a 60 mile round trip and the pump failed again doing 65 on the highway. I heard a subdued whump and then lost all power and had to get towed back to the dealer. This time the failure was due the the hose that connects the pump to the sending unit, it split right down the middle. The mechanic replaced it with a reinforced hose from my original pump, for some reason the new pump hose was not reinforced so anyone buying a new ACDelco pump should make sure you have the reinforced hose. When I got home I changed the fuel filter just to make sure it was not causing excessive back pressure and everything has been good since.

Thank you for your assistance, this forum has some of the best and most supportive people I have ever had the pleasure to interface with on the internet!

Greg