DwayneInBC

Hi everyone. I'll try to give as much info as I can in the hopes someone can steer me in the right direction. It's a 2000 chevy express 1500 4.3 liter. I was driving down the highway, and the motor gave a studder, 5 minutes later, another one. 3 minutes after that, it just died. Get it pulled over, cranked, but no start. Had it towed to the shop I normally deal with (214 bucks). They did a quick look over, then pull the air filter out. Shot some quick start while another cranked the engine. It sputtered, and he said "fuel pump". Next day, they dropped the tanked, replaced the fuel pump. Didny start, said something about reversed wiring, he corrected what ever it was, and it started up. The van was pulled out and left to run while I paid the bill (15 minutes and 641 bucks). Step into the ban, put it in reverse and just died. No crank. The push it back in loll it over and say "blown fuse and bad fuel pump relay". They replaced them, and sent me on mmy way. I made it about a block, and it does again. Eng-1 fuse blew. Can't afford 3 or 4 hours of shop time right now. Spent all I could for now. Had it towed to were I am staying. What I have done far is checked the fuel pump and starter relay (googled how to check a relay) and both seem to be fine. I replaced the fuae with a 25 amp (all I have right now), and even just turning the van on, pops the fuse instantly. I've read various posts to know that the fuse has nothing to do with the fuel pump. Could they have done something when they replaced it?? I'm guessing a melted wire somewhere, but not sure where to look. Would an obd2 scanner give me a hint where to look (I can get a cheap one)? I'm not very techy with a time of tools, nor floor jacks or even ramps, but any advice or direction on maybe where to lookm would so be appreciated. And I do apologize for the long post. Thanks

Gumby22

It’s possible the wiring harness could’ve been pinched when they reinstalled the tank and the damaged wires are causing the fuse to blow; however the eng1 fuse provides power (via ignition switch) to several engine sensors and components. The one near the fuel tank would be the EVAP canister vent valve.

It will take some time but the easiest way to narrow down the problem will be to unplug them all and then plug them in one at a time, turn the key on, and check to see if the fuse is blown. If the fuse doesn’t blow, turn the key off before plugging in the next one.

If you have them all unplugged and the fuse still blows it’s a problem with the wiring harness. The biggest problem areas are the stretch just underneath the engine bay fuse block where it passes near the coil spring mount (easiest access for inspection and repair is removing the tire and fenders liner) and the areas about 6” out on either side of the o2 sensor connectors.

The components that get power from the fuse are:

-all 4 oxygen sensor heaters
-cam and crankshaft position sensors
-EVAP purge & vent valves
-mass air flow sensor
-secondary air injection relay

DwayneInBC

An update. I unplugged then main connector for the fuel pump, tried to move a few wires around. Also tried moving the wire to the is sensor that was in that area as well. Put a new fuse in, and it was fine. Plugged the connector back in and it fired up. Ran good. Had it idling to operating temp, put in drive, reverse, park, help a highernrpm for a while, all seemed fine. Went for a drive, and sure enough, about 10 miles, fuse blew again. Tried replacing it, blew right away. Had it towed back, and let it sit for the night. This morning, put a new fuse it, fired right up. Same as last time, idling fine, put it in drive, reverse, raised the rpm, still runs good.. Turn it off, let it sit, starts up again. Is there something that I'm missing?? Something I can check?? (oh, an no check engine light). Anything, any thoughts would be very helpful at this point.. Thanks everyone

kevinkpk

As gumby pointed out, sounds to me like you have a skinned wire, and at times it is shorting out causing the fuse to blow.

DwayneInBC

That's what I'm thinking too. Im pretry sure it's nothing on top of the fuel tank, since the only wires there should be for the fuel pump, unless someone can inform me otherwise. I know they updated the connector to the fuel pump, but still from what I read, it's not on the eng-1 circuit. I'm thinking it's possible that maybe as he yanked on that harness, it moved something, and it's doing an intermittent short. I will have to jack up the body a little (I'm no small guy) to really get under there and start looking. I think this is going to be a time intensive job... Thanks

Uptownsport

You don't need O2 sensors, EVAP, AIR to run? If not, eliminate those.
It helps to narrow it down from, well, 'it could be 'everything.'

Gumby22

The only component near the fuel tank that would be on the eng 1 circuit is the EVAP vent valve. I can’t recall if it’s ahead of or behind the fuel tank but it’s mounted on the frame rail. The ignition voltage will be on the pink wire - the white wire is the ground side and is used by the PCM for control. If it’s in front of the tank, it shouldn’t be too difficult to open up the wiring harness starting at the valve for inspection. If it’s behind the tank, you’ll have to work the harness loose from its retaining clips (or drop the tank) so it can be pulled down for inspection.

I’m not sure if you’re joking or trying to contribute, but no, none of those things need to be hooked up for the engine to start and run. The O2 sensors, EVAP and AIR systems are all for emissions control - the PCM can still operate the engine without them, though it would be stuck in open loop without O2 sensor input.

DwayneInBC

Thanks gumby.. It's in front of the gas tank on this thing. I tried pulling the cover off (removing the 3 bolts) but something seems to be clipped in along the top, and it's a but dirty (rusty too a bit), and with limited room underneath, it does make it hard. I'll try soaking it in wd-40 to see if it helps. I also have the Haynes manual as well, and I will refer to that in the hopes it will give me a better idea in removing the cover. Last thing I want is to screw something up.. I really do appreciate all your help. I'll keep you up to date. Oh, as of today, the van starts, runs fine. I'm juat afraid to drive. The cost for 3 tows so fsr has really killed my budget lol.. Tha k's again

William Kisselstein

I changed a tank on a 2002 in January. The EVAP purge valve is on the intake manifold.

When you change a pump they all come with a new wiring harness pigtail and you are supposed to change out the entire thing. Did they screw that up and it's shorting somewhere? The wire should have some play on top of the tank. I don't know if you can pull it out far enough to examine where the splice should be. That you said you moved the wiring and it then started and ran tells me this is probably the issue.

Also, on mine the wire passes through a tight spot at the forward tank strap, up on top where the tank upper support is, it's easy to get that pinched, although it should have a plastic guard on it.

The shop who did this repair should drop the tank and examine all this stuff. You can drop the tank too if there's not too much gas in it but it is very hard to do in your driveway, you need to get the whole left side of the van about two feet in the air, take off the inlet, etc.. I had a hard time getting it back up in place, required use of two jacks and a cordless impact on the bolts. Those bolts are something else, I ripped up a brand new one when it cross-threaded, the clip on it tore off. .

The only sensors in that list that should entirely prevent operation are the crank and cam sensors. It will run with the MAP unplugged and give a check light, and I don't think it uses O2 sensor data in closed loop.

DwayneInBC

Thanks for the reply WK. for a while I thought it might have been the wiring up there too, but as far as I've been reading and told, the fuel pump has nothing to do with the eng-1 fuse circuit. From what I've seen from under the van, those are the only wires that lead in that direction. And haven't had an issue with the relay, just that **** fuse. I know there is that box just in front of the fuel tank, one of the O2 sensors lead into that, and I'm going to give a second shot at pulling the cover off and goi g thru those wires. Could be possible that as he changed to the new wiring, they pulled something. Won't know until I can get it off.. At this point, I can't blame the shop on this, since the pump was all they did and its on a different circuit. And I'm out of funds to let someplace else check it. So for now, it's going to be a long slow process.. Thanks