First time my 80 has let me down/towed (1 Viewer)

[scrowley]

So the 80 took its first ride on a tow truck.

I left for a friends party in the afternoon and I noticed on a uphill it cut out 2 times for a second.
I hadn't drivin it in awhile so I filled it up with 93 octane and didn't think much of it.

When I left my friends house the 80 made it about a 1/4 mile and coughed a few times then just died.

It turns over very strong still but no sounds from the fuel pump. I switched EFI relay's but that didn't help
I noticed a melted 15amp EFI fuse right in the same box. I pulled it. cleaned terminal and popped in a new fuse. Still nothing. No fuel pump sound. I might have to re wire the efi fuse to another spot on that panel as it did a little melting.

So I called triple A. I will be looking at it tomorrow.

Just looking for some suggestions.

One suggestion I got from a friend was that a few 80's out there have had harness shorts inside the tank for the fuel pump itself. I will be pulling that out first to check.

 

[scrowley]

Couple pics

 

[ppc]

I would first check the wiring harnesses going to the O2 sensors, close to the sensors near the driveshaft/exhaust and then where it goes over the transmission. The melted fuse is no bueno. It should have blown and not melted. That is a sign of a cheap Chinese fuse. I would look at replacing all other fuses,

 

[jbatx]

Yeash... yes, shorted somewhere down the line.

 

[NLXTACY]

That fuse is a good indication that it didn't blow. Common on Chinese fuses. It's one reason I go to the extent I do to find non-Chinese crap

 

[scrowley]

I'll defiantly visually check the harness before getting into the fuel pump end of it.

I was never aware of cheap fuse's that don't blow... interesting.

 

[bloc]

That fuse controls power to nearly every 12v sensor or solenoid on your engine, as well as the fuel pump. So there are a lot of possibilities.

95+ have issues with the harness shorting behind the glove box, in the tank, and in the main harness near the EGR flow tube. Fuel pump is relatively easy to check without opening the tank.. there is a 6 or 8-pin connector under the body below the driver's side second row seat. This leads to the tank. Bust out the EWD and figure out which color wire provides power to the pump.. I'm not sure how a normal pump would Ohm out but if the short is in the tank this wire will have very little resistance to ground.

 

[OGBeno]

That fuse is a good indication that it didn't blow. Common on Chinese fuses. It's one reason I go to the extent I do to find non-Chinese crap

OEM fuses are still Hecho in Nippon.

 

[CycloSteve]

One suggestion I got from a friend was that a few 80's out there have had harness shorts inside the tank for the fuel pump itself. I will be pulling that out first to check.

I had the ground in the tank for the fuel pump give up the ghost. Exact same instant engine cut, as no fuel delivery...but mine did not burn the fuse like yours. If the power feed shorted, the fuse should have blown. I replaced the ground wire from the pump plug to the grounding point inside the tank and all was better. You may need to replace the harness in the tank, or the complete assembly.

On a related note, I wonder if the high ethanol in the fuel now is degrading the insulation on the wires. My ground definitely felt degraded/soft.

 

[OGBeno]

I had the ground in the tank for the fuel pump give up the ghost. Exact same instant engine cut, as no fuel delivery...but mine did not burn the fuse like yours. If the power feed shorted, the fuse should have blown. I replaced the ground wire from the pump plug to the grounding point inside the tank and all was better. You may need to replace the harness in the tank, or the complete assembly.

This happened to me as well coming back from Rubithon 2009 on I-40 near Williams, AZ... NOT FUN.

 

[landtank]

You need to figure out which side of the fuse melted before blaming anyone. If that is the source or feed side on the fuse and it happened to have a less than good connection its likely that bad connection that melted the fuse because the amps never got high enough to trip the fuse.

Melted components is almost always a connection problem.

Now if someone could confirm that the blade thickness on these Chinese fuses were thinner that they should be and caused the bad connection, then that would be a different story.

 

[scrowley]

Blade thickness on the fuses measured the same.

 

[scrowley]

So I went through the fsm on the fuel circuit.
Tested most all components. Took fuel pump out to inspect. Looked great. Pump ran with direct 12v. All wires checked out ok.
Truck fired right up. Sweet..not... I went for a ride and it lost power again for a couple seconds then came back. I made it back to my shop running normal.
I placed order for fuel pump relay even though it tested out fine.
Both efi relay, and one in driver kick a replaced with new ones I had.
So any other suggestions?

 

[bloc]

Did you check the harness by the ECU where it wraps around a bracket?

Also how bad was the socket in the fuse block after it melted the fuse that badly?

 

[1973Guppie]

That fuse is a good indication that it didn't blow. Common on Chinese fuses. It's one reason I go to the extent I do to find non-Chinese crap

honestly I would like trump more if he banned chinese fuses, just sayin.......

 

[1973Guppie]

first thing I would be doing is inspecting the harness like crazy in order to identify any issues that can be transient.

 

[rc51kid]

Also start looking in the last place you worked on anything. One time on another car i had puched the harness and exposed some wires during the install of a batt. The wire would contact metal and ground out during left hand turns cousing intermittent problems. I know that is not your issue.

It tought me to carefully inspect the last place i was working.

Strange stuff like "i changed brake pads and now my turn signals dont work...". Sometimes you find that you did something strange like a pry bar bumped a conecter. Two things look unrelated sometimes but i dont belive in coincidences.

 

[scrowley]

Well @rc51kid. I put a new long block in 4000 miles ago...
I worked as meticulous as I could.
So I haven't done any work in it since then. I have multiple wheeling trips since then.

I recently bought a new car so the cruiser has been sitting a lot. I hadn't driven it for a couple weeks the day this issue started.

 

[scrowley]

Did you check the harness by the ECU where it wraps around a bracket?

Also how bad was the socket in the fuse block after it melted the fuse that badly?

I didn't check there but when I put a new long block in i wrapped the harness in that area.
The fuse block looked ok still. Melted it just slightly. I cleaned up the terminal a little.

So I've learned that fuses melt from bad contact. So yes it's still on my mind that the fuse block could be an issue. Maybe when fuel pump kicks into high it's drawing more power that the terminal can't handle. Idk how to test that though.. a line clamp amp tester maybe.

 

[bloc]

If you remove the bottom of the fuse block you can extract the terminals and bend the pins inward to make better contact. Also do a much better job of cleaning up any carbon that has built up. You may have trouble getting it out due to the melting.. a used fuse block isn't too difficult to find.

Our fuse terminals aren't absolutely bomb proof.. I've had three blocks open while I did my engine swap and two of them had slightly overheated terminals at one of the headlight fuses.. and to be specific the problem was at the crimp to the wire, not at the fuse clamp end of the terminal.

Either way.. many thousands of rigs aren't burning that terminal under normal operation. If it's "too much" current for some reason it should just pop the fuse.. so to me it points toward that terminal needing some work.