LC100 won't crank - No power to the fuel pump (1 Viewer)

[cbbr]

2000 LC 100. It started last night and died twice. Then (and now) it won't crank. It sounds like there is zero fuel. The battery is strong and I have checked all of the fuses. I pulled and tested the fuel pump and its fine.

I then tested the power to the fuel pump with a test light and there is n power while key on or cranking.

I also ran a code reader with the key on (obviously the engine was not running) and there are no faults shown.

 

[cbbr]

The security light does not come on.

I reattached the plug to the fuel pump and tried the "pos to ECU Relay terminal F" with no success either. It cranks strong, but the fuel pump is not pumping.

I put it in neutral and tried to start it - nothing.

 

[3_puppies]

does your rig have a reset just to the right of your right shin when sitting in the driver seat?

 

[cbbr]

Yep. Held it for ten seconds with the key on. Turned the key off/on and tried to start it - nothing.

 

[kevgentile]

Really need to check for faults and look at live data. It could be any number of things, cam or crank signal, faulty relay, etc.
Best to be armed with as much info instead of guessing.

 

[cbbr]

I used GaragePro/OBD and the only fault that it showed was an ABS code. Obviously it would be better with the engine running. Is there a better way to check given that the engine won't start?

The problem appears to be electrical as there is no current to the fuel pump with the key on or when cranking.

 

[kevgentile]

I used GaragePro/OBD and the only fault that it showed was an ABS code. Obviously it would be better with the engine running. Is there a better way to check given that the engine won't start?

The problem appears to be electrical as there is no current to the fuel pump with the key on or when cranking.

Lets say hypothetically it's a crank sensor. If not sending the proper reference signal to the ecm the ecm should disable the fueling circuit so it doesn't wash down the cylinders. like I said, it can be a number of things to look at so having diagnostics to observe live data is tremendously beneficial. It doesn't need to start to find errors. Cranking the engine while observing the signals/data will provide you with a lot of answers.

 

[kevgentile]

Another option is to print out the voltage specs from the wiring and diagnostics manuals and meter the circuits. It's time consuming, but an option if you don't have access to proper diagnostics.

 

[cbbr]

That may be what I have to do unless I can borrow a far better diagnostic tool than my obd reader. Some days...

 

[SteveH]

@cbbr The problem appears to be electrical as there is no current to the fuel pump with the key on or when cranking.

Check the harness under the driver's side rear door for corrosion at the bend point. Mine was ummm... compromised there, and the fuel pump ground wire had 9.8 megaohms resistance, right before it had infinite resistance. Story and pix here: Fuel pump wiring failure - and the fix - https://forum.ih8mud.com/threads/fuel-pump-wiring-failure-and-the-fix.1325429/

 

[cjmoon]

crank position sensor or EFI relay it fires the pump.

 

[cbbr]

crank position sensor or EFI relay it fires the pump.

Any way to test for those, or do you just replace things until something works? The tach needle does not move at all while cranking if that's a hint.

 

[kevgentile]

Any way to test for those, or do you just replace things until something works? The tach needle does not move at all while cranking if that's a hint.

Tach won't appear to move while cranking. Live data will show it only spinning roughly 160 +/- rpm.
The more the reason to get the diag and a meter. The manuals are here and have all the info you need. They can be a bit difficult to follow and you can get lost in them but take the time and become familiar with the info, it'll pay off in the long run.

Don't just shotgun it

 

[Bomar]

Hey went through same thing had truck towed back from Yellowstone and come to find out it was fuel pump.

Go OEM fuel pump bought one to just get me home and it didn’t work correctly out of the box.

It was a $3k lesson learned

 

[cbbr]

Hey went through same thing had truck towed back from Yellowstone and come to find out it was fuel pump.

Go OEM fuel pump bought one to just get me home and it didn’t work correctly out of the box.

It was a $3k lesson learned

Thanks - I pulled the fuel pump and it runs fine out of the tank. That would have been far too simple...

 

[Bomar]

Same thing here brother. I am telling you.

Is it OEM? Make sure it is putting out enough pressure.

I sent my truck to a friend and had him check every wire since I got no power to fuel pump. After ohming and checking every wire he said to hell with it and pulled a known good fuel pump out of a parts truck and no issues since.

I even had a new ECU shipped in.

I sat on side road worked on truck for 10 hours.

 

[cbbr]

I honestly didn't pay attention to whether it is OEM and I'm not the first owner. Everything appeared untouched when I removed it though. I'm not against pulling it and checking it again. What I did was the simple redneck bucket test.

I do know that the PO changed the o-rings on the injectors and at least one of the injectors, so those are on my list to check as well as the crank positioning sensor.

 

[cbbr]

This thread is the "history" of the fuel issue. The PO changed all of the fuel injector o-rings and one injector. He also put in a new fuel filter. The truck ran great when I bought it. I am starting to suspect that there were issues other than the injectors and fuel filter but can't explain why everything ran so well for a week.

Any suggestions on the best (and/or easiest) way to test the fuel pressure?

 

[jerryb]

if I was still in lafayette I'd drive an assembly over.
I don't know if you can, but tech stream can run the pump if you're set up for it.
I don't usually get involved in pre vvti but..
there are end ports on both rails, double banjo for the crossover pipe.
I'd still think electrical.
Don't know if there's an C OPN relay, I'd techstream for relay checking, check grounds and work backwards from the glove box ecu.
Then there's that efi fuse on the early 100s. Honestly, I'm not schooled in 98-2005 injection/throttle.

 

[cbbr]

I am now the proud owner of a HF Basic Fuel Injection Service Kit. I got hooked up and turned the key - zero pressure. So I then ran a long jumper from the battery to the top of the pump to manually run it and I get 45PSI. It holds at over 23PSI at 5 minutes. Per the FSM, that is spot on when measuring with a Chinese gauge.