EFI Relay Questions

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jakesiar

jakesiar

15 Year 10 Year
Joined
Jun 15, 2009
Threads
49
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445
Location
Raleigh
I have searched the board and read the posts regarding the EFI relay wire fix and I plan on doing this... I have been chasing down a hesitation/no acceleration issue. I have changed plugs/wires, fuel filter, fuel sock, TPS, cleaned throttle body by removing it.
If the EFI relay is getting too hot would it cause this stumbling/hesitation?

Thanks in advance and Merry Christmas!
 
Jonheld, thanks for the response. I have a '92 with ~195K on the clock. I get a random no acceleration at a dead stop and sometimes while I am driving. The engine doesn't stall it just doesn't go. It is random and can occur with a cold engine or hot... I also replaced the fusible link and all parts are OEM.

Thanks, Jake
 
jakesiar said:
I get a random no acceleration at a dead stop
Click to expand...

Explain in more detail. You're stopped at a red light. Light turns green and you step down. What happens exactly?
Does it happen only when the motor is under load like taking off from a stop or uphill?
 
Intake replaced within the last few weeks also... I could be stopped and press the accelerator and it acts as if it is not getting gas but it does not stall. It will do the same thing at times while driving, it boggs down and then will accelerate as normal. Last night I popped the hood and the EFI relay was burning hot. I thought possibly this could be related.
 
The EFI relay will always be hot. It lives above the exhaust manifold. That fusebox is like a slow cooker.

I could very well be poor connectivity in the fusebox from heat and corrosion. You're going to need to do more investigating. You could try the percussive approach. With the motor running try moving stuff around and localize the issue.

Knocking on the relay can will almost always cause a stumble if you hit it hard enough, however slightly moving the relay shouldn't be an issue unless the contacts are poor.
 
Does the '92 have a fuel pump relay?
 
It has a "circuit opening relay" in the left kick panel. It is essentially the fuel pump relay. It has 2 coils. One gets energized by the starter circuit and one is energized by the opening of the AFM flap.

You can bypass all FP logic and feed it directly with +12 by jumping pins 1-8 on the check connector. I recently went through this with someone else on this thread:
https://forum.ih8mud.com/80-series-tech/540240-3fe-fuel-issue.html

Lots of good info.
 
Had the injectors out & flushed? -Sorry if I missed that & you have.

Also, is a '92 wired like a later model where there's a connector under/outside the body on the driver side just under the rear door? Damage or corrosion to it? I replaced my floor harness (e-locker conversion) & didn't fully seat that connector & I flat didn't start until I traced it back.
 
LINUS said:
Had the injectors out & flushed? -Sorry if I missed that & you have.

Also, is a '92 wired like a later model where there's a connector under/outside the body on the driver side just under the rear door? Damage or corrosion to it? I replaced my floor harness (e-locker conversion) & didn't fully seat that connector & I flat didn't start until I traced it back.
Click to expand...

With regards to the injectors, they have not been removed and cleaned. I have run BG44K and Redline Complete Fuel System Cleaner (currently running through). As an FYI, both products seem to smooth out the idle and the car drives absolutely great with the exception of the random hesitation/ no acceleration.
 
jonheld said:
Explain in more detail. You're stopped at a red light. Light turns green and you step down. What happens exactly?
Does it happen only when the motor is under load like taking off from a stop or uphill?
Click to expand...

OK, now the hesitation is occuring more and more but does remedy itself (whatever that is) and go away. The truck will then run fine and idle very smoothly. I have noticed that I get some popping/backfiring from the passenger side when it is going through this. Any ideas...?

Would a fuel pump on its way out start to cause this?

Thanks in advance... Happy New Year!
 
Have you checked the exaust system? Possible plugged cat or crunched tail pipe blocking flow? I am just shooting these out there as idea's. :confused:
 
It may not be an issue in an older LC like yours (IDK, I know it's a 1FZ thing, but maybe a 3FE has engine wires routed the same way?)

Anyhow, there's some wires behind the glovebox that chafe on the firewall & short out - just a potshot & at least in my experience, failing fuel pumps tend to act up more when the tank is lower, less so when you're running with plenty of gas in the tank.

Do you find it happening more when there's less fuel in the tank? Ehen it's happening, can you pull over, key off & then restart & it's better? If so, I'd swap the fuel pump - and really check that connector coming off the floor harness underside the 80 if you haven't (underneath RR LS door)& grease the terminals.
 
94 hesitation, no acceleration, random

my 94 does the same thing, and I have checked, wires in harness behind EGR, changed plugs, wires, distributer cap, coil, fuel pump, sock, air intake hose, fuel filters, egr valve, Do you have pictures of wire harness behind glove box? do you have to pull the dash off? Is it easier to find from under the hood? next I am looking at replacing relay in left kick panel. Someone said TCU? Transmission control unit? anyone? Another thing it has a propensity maybe 3 out of 10 time to do it after a right hand turn. otherwise it can happen driving straight, load, no load,in neutral or not. HELP. this randomosity is driving me crazy :bang: :P
 
AZ 80 said:
94 hesitation, no acceleration, random

my 94 does the same thing, and I have checked, wires in harness behind EGR, changed plugs, wires, distributer cap, coil, fuel pump, sock, air intake hose, fuel filters, egr valve, Do you have pictures of wire harness behind glove box? do you have to pull the dash off? Is it easier to find from under the hood? next I am looking at replacing relay in left kick panel. Someone said TCU? Transmission control unit? anyone? Another thing it has a propensity maybe 3 out of 10 time to do it after a right hand turn. otherwise it can happen driving straight, load, no load,in neutral or not. HELP. this randomosity is driving me crazy :bang: :p
Click to expand...

I know this is 8 years later, but was this issue ever resolved?
 
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