forum newbie | '92 FJ80 - - Hot weather mean no start

[murf]

I used to work with a well renown Landcruiser tech in Phoenix that had a huge following (too bad he moved to Montana). I have seen him a several occasions fix this overheating EFI issue. His diagnosis and solution was to rewire the fuse box for that relay with larger guage wire. Fixed it every time permanently. One instance had the fuse box actually melted to the point he had to get a replacement from Spector Off Road and do it up. Takes time and patience but the smaller guage couldnt handle it and overheats/pops fuse. Hope this helps...

 

[pnwadventurer]

Not to hijack the thread, two weeks ago, in 80 plus temperatures and with a lot of low range driving, I experienced one hard starting situation (as described above) and multiple episodes of not being able to get rpms above 2000 until I allowed the engine to cool.

Would this be another symptom of the efi relay overheating?

I like the idea of relocating the relay to the interior. I will add it to my list of things to do.

 

[FrankTorres]

Frank,

Could you do me a favor when you get a chance? Throw an ammeter accross the load side of the EFI relay and measure the current that the EFI circuit draws at idle and while under load. .

Jon,

I do not have a way to measure AMPs other than using fuses...
I used a 10A fuse (that was the lowest I had) and it did not blow.
Toyota has a 15A fuse for this load side circuit.
I believe the EFI Relay's sole purpose is to supply the ECU with power from the battery.

The relay that draws the AMPs is the Open Circuit Relay which supplies power to the fuel pump.

PLEASE correct me if I'm wrong... I'm no expert just play one on the net

 

[FrankTorres]

60 miles of stop and go in the Texas heat with 4 or 5 hot starts and I report 100% success.
Started up every time.
It's only day one though but I am confident about this fix...

Another thing is that you are not restricted to a particular relay.
I tested a couple relays I had and all worked, Toyota and generic relays.

 

[jonheld]

The EFI circuit feeds +12 to the ECU, all 3 VSV valves, both O2 sensors, the ISC valve, and the load side of the circuit opening relay which feeds the fuel pump when the motor is running.

Basically the whole shooting match. After I rewired my fusebox I took some current readings accross the load side of the EFI relay and I remember them being way lower than I imagined. I wanted a second opinion on this. I might get a chance to test again later today.

Everyone says the wiring is undersized, but my first reading doesn't agree. When I removed mine the insulation was brittle due to heat and the connections were severely deteriorated.

I theorize that the combination of manifold heat and poor crimps from the factory compound themselves over time and cook things to death. While I have found my share of bad factory crimps and corroding connectors over the 16 years I have owned this truck, the EFI circuit is the one that gets all the attention simply because it is always in use.

Or I could be full of poo.

 

[FrankTorres]

I agree that the amp draw on the EFI circuit is low.
I also agree with you Jon that the wiring is not undersized for the load and that the relay and connectors get cooked over time by the extreme temps under the hood.

Before I relocated the EFI relay I had done the wire upgrade to a heaver gauge and a new EFI relay. This worked for a few years until the relay started to fail again this summer.

I would also like to see some amperage numbers across the EFI relay.
If I'm not mistaken the fuel pump should draw around 5 to 7 amps

 

[INNOV8S]

Intermitent Starting Problem - Today = humid, rain

Problem Log - Aug 15th

Parked inside last night - did not start right away, several attempts to start. Pulled relay out; it was cool. Eventually started - - seemed like a 3/4 turn did it.

Drove to work, parked all day - - overcast and humid. Tried to start, multiple times, no luck. Called wife for a pick up. Now raining.


I suspect ignition/key interface, seems loose. I had this replace 1.5 years ago, so I am unsure.

Also suspect O2 sensor, again had these replaced 1.5, or so, years ago.

Help! I'm gone sell this unreliable ride.

your comments appreciated,

Gil

 

[TRIDETOY]

efi relay

I am having same problem with 91.I had wiring upgrade done in phoenix years ago .Then problem came back.I need to find out how to permanetly fix.A trick a mechanic in Phoenix showed me to get it started is to pull relay and run jump wire from two pin sockets closest to center of engine bay.It will start and run thisway but you have to remember to undo wire.If you forget it will drain battery because computer stays on.

 

[drnls]

Gil - when it doesn't start is there any clicking or noise from the starter like it wants to start or you turn the key and nothing? You have a new distributor and the contacts were cleaned. What contacts? Has the starter been pulled and the contacts there been replaced? I recently had a no start issue as well. I disconnected everything from the battery - cleaned with wire brush and steel wool. Also pulled the starter back out, cleaned the contacts in there as contact with the plunger was uneven. I reinstalled the contacts as directed by the manual with pressure on the contacts, added a new plunger. Cleaned the wire connections to the starter. Once all connected it started like it should - going three days with no problem. Nelson

 

[INNOV8S]

Magic - the jumper wire worked!

Tridetoy,

Most excellent. Your tip made my ride fire right up! Can I hot swap back the relay? ...that is, when it is running.


What is the long term fix? New relays? Bigger, performance relays? Camry relays?

Thanks a ton for the tip, at least i can get it started when stranded, which has pretty been all of the time lately.

Gil
on Lake Michigan

 

[jonheld]

I suspect bad terminals in the fusebox, but I've already said that. No you can't pull the EFI relay and keep the truck running...have you read or understood any of my posts?

 

[INNOV8S]

Jon,

Thanks for the reply. Yes, I revisited you site and there seems to be a ton of info there that I glossed over the first time. I'm not boned up on electrical stuff, nor extremely hands on. I've gotten to be with this issue.

To your point just a new relay might not be a permanent fix. I want to check the connection points under the EFI relay. Does this box remove easily?

Today the CEL was not coming on in the "ON" position, with the relay in. Not sure if it came on with the 'jumper wire' in.

Gil

 

[INNOV8S]

Jon,

why do you have that secret, square, green, voodoo relay in one of your photos. Whats the deal?

Gil

 

[jonheld]

Gil,

If the CE light isn't on, then the EFI circuit is not functioning. The truck won't fire regardless of how many chickens you swing over your head. If you read the info on my website there is a step by step diagnostic procedure to determine where the problem lies. Obviously it is an intermittant issue so IMO it could be bad/corroded contacts in the fusebox or an intermittant fusible link. Without going through the diagnostic steps it is impossible to tell where the problem lies. That is up to you and all you need is a multimeter which you can pick up at any Radio Snack. FWIW, I would replace the fusible links as a PM item. They're very inexpensive and easy to do. That would rule one possibility out.

None of the fusebox stuff I did was difficult, just time consuming. I made up a new harness inside the fuse box for the EFI circuit using the OEM connectors I bought.

The green relay is from a Camry and the part number is listed on my site as well.

 

[photogod]

Vapor lock? Is your intake cooling fan blowing on the intake tubes? Seems to easy...

 

[jonheld]

Everyone says the wiring is undersized, but my first reading doesn't agree. When I removed mine the insulation was brittle due to heat and the connections were severely deteriorated.

I finally had a chance to re-measure the EFI circuit current. I got between 6.25 and 6.5 amps from idle to 3000 rpm. I either measured incorrectly the first time or I was accross the coil side of the relay. In any case, I updated my web site to show the findings.

While the stock wiring is capable of handling the current, it is close to its tolerance. Add in some questionable crimps, throw in some heat from the manifold and you have an unfavorable situation.

 

[FrankTorres]

Thanks for the number Jon...

 

[dallen341]

I finally had a chance to re-measure the EFI circuit current. I got between 6.25 and 6.5 amps from idle to 3000 rpm. I either measured incorrectly the first time or I was accross the coil side of the relay. In any case, I updated my web site to show the findings.

While the stock wiring is capable of handling the current, it is close to its tolerance. Add in some questionable crimps, throw in some heat from the manifold and you have an unfavorable situation.

I'm having issues as well and just measured load across the load side of the relay. At 2000 rpm's 6 - 6.5A and @ idle about 7.25A or so.

I wonder what the relay is rated for @ continuous duty.

Don

 

[dallen341]

I suspect bad terminals in the fusebox, but I've already said that. No you can't pull the EFI relay and keep the truck running...have you read or understood any of my posts?

I have to agree with Jon on this. I was making a simple temp harness that would allow me to pull the relay into the cab. I noticed that the .25" spade terminals for the coil harness I made fit tight into the relay socket located in the firewell fusebox. The terminals for the contact side were extremely loose. Examination of the spade terminals on the relay itself indicated burning/arcing had occured. No doubt from the loose fitting terminal into the socket.

So, loose terminal = high resistance = more heat generated. I tweeked the terminals in the fusebox to make for a much tighter terminal fit an d added dielectric grease. Time will tell if this proves to be the fix.Don