I have just completed a complete rebuild about 500 miles ago and have blown 2- 15 amp fuses since then. It is more of an anoyance than anything but I want to figure it out before the problem worsens.This is no longer an anoyance because I now cannot get off of my street before the fuse blows As an aside I also had to replace my main EFI fuse in the begining of the rebuild. This is the large round metal fuse in the drivers kick panel.

Thank you in advance.

 

You sure someone didn't jam a nickel in there? That's what my Gradaddy used to do to find the problems.... Put a coin in place of the fuse until he found where a short/grounded wire was... Lol

You're sure all wiring is ok and nothing got nicked when putting it back together?

I would retrace everything by hand just to verify, at least everything in that circuit. Maybe something got pulled and cut up a little?

 

When I said EFI main fuse I should have said EFI main relay.

 

Blowing a fuse is considered a short-to-ground fault. That's when the elcerticity finds a connection to ground prior to the load itself. The circuit has no resistance (no load) and therefore high current travels the wire.

Or you also may have a component in the EFI system that is drawing too much current causing the fuse to blow.

With a short-to-ground, you would need to look at the wiring schematic at look at the wires prior to the EFI load.

 

I chased all the wires in the truck that I could think of for the fuel system, including taking out the passenger seat and glove box to look at the wires for the fuel pump and sending unit. I'm unsure what wires to look at under the hood.

I've put 500 miles on this rebuild and today rechecked my valve lash, and changed my oil and since then I've blown 3 fuses.

Thanks for any more help guys.

 

You need to get a Factory Service Manual wiring diagram if you don't have one. At least a Haynes/Chiltons is helpful but not always very accurate. FSMs can be inaccurate too though. Anyway, the EFI circuit isn't just for fuel system if I recall correctly. That's why you need to trace the circuit.

 

Does the fuse open right away??

When you turn the key on??

When the engine is started??

Or does it work fine for a few miles then open leaving you sit till you install a new fuse??

 

I have a Haynes Manual the diagrams in there are less than helpfull. I pulled off my fuse panel from the driverside kickpanel and all the wiring looks good there. Should I try to mabey put a 20 amp fuse to try to get by this problem or will that just fry something?

It starts when I put in the new fuse, Idles in the driveway and about 1/2 a mile down the road...pop. I haven't been able to get off my street for a couple of days.

Also I have the fuel test jumper installed. I've had this in for years. I pulled it out and put a new fuse in and as soon as the motor fired the fuse blew. I don't know if all these things are related or not but I figured I'd relay them to you.

Thanks guys

 

Could I have messed up the wiring for the sensor directly below the oil filter. I cannot change the oil without drenching that thing, so yesterday I unplugged it while changing the oil. That is the only thing I messed with.

Anyhow I'm going outside right now and I'm gonna unplug and check every single connector on the passenger side of the motor where they come up to the intake manifold.

 

Okay here it is, I just got done with checking the wires under the hood. I pulled out the entire loom of wires that is on the passenger side of the motor and when I split the intake I noticed that the insulation on injector plugs 2 and 3 were cracked in several places and bare wire was showing. So I seperated ALL of the wires on that side and cleaned them up and wrapped them with high temp electrical tape (3M super 88). I cleaned and wrapped every plug from the AFM to Injector #4 and the VSV down to the oil pan.

I went for a 15 min test drive and no issues. Also I did not replace the test jumper for the fuel pump. So my question is do y'all think that the injector wires could have been grounding out on the fuel rail or motor and poping the fuse or did I just get lucky on my test drive.

I ask because I would like to go hunting and I don't want to break down off in the woods 2 hours from home, know what I'm sayin'?

 

A couple things...

Was the wire insulation melted or discolored from heat?

Were the bare wires touching metal at the time you noticed it?

Without knowing what the color of insulation wire those are, you wont be able to tell if those bare wires were on the positive side, suppling 12 volt power, or on the negative side. If those bare wires were on the positive side then the answer to your question is, Yes. You would have had a short-to-ground. But again, you would have to determine what color insulation those wires are, then check the wiring schematic to determine which side of the load they are on.

If those bare wire were on the ground side, then you would have had a miss-fire, as the injector does not have a proper circuit. The injector would only operate sporadically.


All of this typing is only speculative as you would be the one to verify what I or we say is correct or false.

 

Well a few times before I did this wire clean up I did have the occasional misfire but I have not noticed any since.

The injector plugs were taken from another vehicle and they were connected and heat shrunk correctly. The splits in the insulation were in the insulation in the 2 inches of insulation from the "new" plugs. They look like they were just from age like mabey from sitting in the junk yard in a car without a hood. South Florida sunburn.

Also I did go hunting and have put about 300 miles on my truck in the last 3 days including some mild off roading to get to a fishing hole. All without any issues so far....

You guys rock and hopefully this helps someone else later.

 

Good job bro! You did this mostly all on your own. Excellent, excellent, excellent!!

 

i bet it felt good to know you fixed it right, i remember how i felt after i fixed the big problem in my truck. Congrats man and good job in finding the problem.

 

Thanks Again guys, I've been getting in some end of the season duck hunting. I just put about 500 more miles on the truck in two days. Driving around with a canoe on top does not fare well for the fuel economy! But I haven't burnt any oil or used any coolant so I'm stoked.

 

I usually run with a 14ft yak on top of mine. Doesn't seem to bother my fuel economy. But I do ride slower because I'm scared of it flying off....