I don't want to make a new thread but I can't find what looking for. So my 91 22re pickup had a sputter issue I replaced the AFM and it ran great for about 100 miles, 70 in the cool morning and 30 in the afternoon heat. On my home the EFI fuse blew twice in a row while driving then I towed it home and it started and ran fine. What I was wondering is what are the chances that a hot igniter can cause it, or I put a fuel pump (a cheap one) in it when I got it 3 weeks ago cause it was siezed up wondering if maybe it's garbage and causing it. Just brainstorming

 

Yeah, could be all that.

But MUCH more likely: you've got a loose wire (or a wire where the insulation has rubbed through) that is momentarily shorting to ground.

One way to keep an eye on this is with this gadget: http://www.harborfreight.com/30-amp-...ter-67724.html . I DON'T know, but I think you plug your fuse into this gadget, so if you really do get a short it will blow the fuse (and not the meter!)

So if it's something like a hot igniter or jammed fuel pump, you will see the current steadily rising until it reaches 15amps. What I think you'll see is it steady at something like 4 amps, then BAM the fuse will just blow (when your bare wire jiggled into the frame).

 

Thanks for the quick response and good idea I actually have that tool (haven't used it yet) but planned to haha! I know this is an incredibly over asked question, but where are some common places for a short? It's not the o2, I checked and I ohmed fuel pump wires up to where they connect under the passenger seat and they are good. And I started the truck and wiggled and jiggled the hell out of every wire and connector that has anything to do with efi fuse and got nothing unusual.. Also I have mentioned in another thread that my efi relay under the hood gets pretty hot as in I can't touch it long enough to unplug it sometimes. just throwing that out there.

 

I would also check the wiring for the O2 sensor likes to melt causing a short.

Have you also changed your fuel filter?? Removing and moving lines can cause all sorts of dirt to come loose and clog the filter

Then cheap fuel pumps are just that . Have wires rubbing from when you changed the fuel pump??

Sounds pretty much like a short because it seems to be intermittent

Loose connection at the AFM plug causing things to arc and draw more current.

 

I would start by replacing the efi relay. it is probably either damaged by the problem, or is the problem. check the terminals in the plug, as they might be blackened and create heat/resistance.

 

I'm blowing that fuse, bummer. Just had the o2 sensor replaced. Gonna check those wires whe n the sun comes up!

 

Just an update I have checked these things and still having the same problem so far the amperage is staying about 7-7.5 across the fuse but I wasn't able to check it when it blew cause the battery died to the tester. I have noticed when the fuse blows both times was when accelerating moderately from a slow speed or from a stop and the engine was slightly above normal operating temp (which I also need to address). After it blew I pushed it off the road cause I was in an intersection and replaced the fuse and all was good. I'm getting pretty frustrated and about ready to sell it cause I need a reliable work truck and I refuse to drive my other truck that much. So it anyone has ideas by all means I'm all ears!

 

One of those things loose connection causing an arc which draws more current causing the fuse to open

bare wire shorting to ground.

both of these conditions caused by movement

Bad engine mounts or transmission mount allow enough movement to pinch something??

Enough suspension movement to pinch some wires ??

wires that should be secured moving ??

It just takes a touch of a wire to ground to open the fuse.

It can be any place in the circuit that draws power from the fuse.

 

while it's cool, get under there with a small mirror and flashlight and look for chafing on the o2 sensor wires. put a new battery in the meter and measure curent to the fuel pump especially while decellereating, or not-running.

 

So what if I take a hose and water down the harness that should short the wire and blow the fuse right? Unless the short is to a ground wire protected by loom but in theory if the wires are safe in the loom they shouldn't be shorting right?

 

Did you ever find the issue with yours?

 

Water isn't typically a good enough conductor of electricity to blow a 15 amp fuse. At 120V it'll conduct the 10-100 milliamps necessary to fibrillate your heart, but at 12V it won't conduct the 15 amps necessary to pop the EFI fuse. Wiggling the wires is a better technique.

 

i'm having the same issue but only when it rains

 

What issue, your blowing the efi fuse well what have you checked?

 

Happy New Year!
Second that. Have you checked where rainwater comes in contact with electrical parts? That would narrow your search.
EFI? Fuel pump? igniter? sputter?
A problem well-stated is almost solved.