Ford LRG - 425 starting problem

[CharlieVT]

Gents,
Grove AMZ66XT manlift I have refurbished. Built in 1999.
Engine is Ford LRG - 425 (carbureted, dual fuel propane/gasoline, but I am running only gasoline).

One problem I've been working around, looking for suggestions:
Starts fine when cold. When hot, after shut down, later it won't restart. It will crank but won't fire.
Once running, runs fine.

I discovered if I leave the electric circuit on after engine shut down then it will restart later.
This works if I shut down with the emergency stop button on the platform control panel or the ignition key on the lower control panel.
So during the day, if I shut off the engine, I'll immediately turn the key back on and leave the key on without the engine running. Or if up on the platform, I shut off the engine with the emergency stop button, but immediately pull the stop button back up. If I do this, it will restart later.
If I shut down the engine and leave the key off or the emergency stop button in the down (off) position, later it may not restart for several hours. It will crank, but no spark.

I suspect the ESC (electronic spark control module) or maybe the distributor mounted ignition coil.
Is this behavior consistent with a failing ESC?

Any suggestions on where to look?
I have wiring diagrams, VOM, and other basic troubleshooting items.

 

[stephan neron]

the choke only the choke when cold it supose be totaly close and opening 1/8 to 3/8 when cranking and full open when hot

 

[CharlieVT]

Merci bien. Stephan

I had moved on beyond thinking about carb and choke. I was using an inductive timing light to check for spark, but that isn't very reliable. Maybe it isn't a spark problem.
I had rebuilt the carb and choke mechanism but tried to keep original settings. My service manual doesn't have a section specific to this choke. This "automatic" choke has an electric heater (which is always on when key is on as far as I can tell), an adjustable bi-metal strip which allows change of choke response to temperature, and an adjustable vacuum mechanism.
Any suggestion on sequence or method of adjusting the choke?
Like: start with cold setting, then adjust cranking setting?
Or set choke at hot setting, then adjust cranking setting?
Disable ignition so vacuum setting can be set while cranking without engine starting?

Thanks again,
Charlie

 

[CharlieVT]

Okay, I found this:
Quote: "
Here's how to adjust these Zenith model 33 carburetors:
If your shop's ambient temperature is 70° simply open the choke plate 1/32" so it is just off the choke bore.

1. If not 70° loosen the three plate screws to open the choke plate 1/32". Then adjust for temperature by rotating the choke cover one mark per each 5° of temperature difference from 70°. Rotate counter clockwise to lean the mixture if warmer than 70° and clockwise to enrich the mixture if colder than 70°.
2. Re-tighten the cover plate screws and check the choke shaft for free operation.

Now I am looking for instructions on adjusting the vacuum setting...

 

[TheFixer]

You need to determine if you have spark or gas before deciding which one to work on. Get an extra spark plug, and pull a wire and check the spark when you crank it. You need to eliminate one.

I think these carbs also have a fuel shut off solenoid on them. I would look at that. Possibly sticking.

 

[CharlieVT]

Well, I have confirmed that the problem is with the ignition.
Spark is lost when engine is hot and won't restart after shut down.
Stays running fine. Will restart if key is left on (power to ignition circuits stays on); key left on seems to maintain the circuit somehow.
But if engine is shut off and left off when hot, there is no spark when cranking to start later. Have to wait minutes or hours to get spark back.
Coil pack is okay.
I suspect the "universal electronic spark control" (ignition module) is going bad.

Any suggestions on where to find one? Ford part no. 12A297.
No luck searching the internet for this part. If anyone knows where to get one, I'd appreciate the info.
Thanks,
Charlie

 

[Birken Vogt]

http://www.edi-dist.com/distributors/

Or try Powertech Engines in Fresno, Ca., they are the old time distributor of the Ford line.

 

[DavidL]

I would replace the crank position sensor first. $20 at O'Reilly's auto parts. Takes 15 minutes the change. 2.5L Ford Ranger.

 

[CharlieVT]

Thanks to all who have replied so far.
Status Report: I did change out the crankshaft position sensor. It did cost less than $20 at O'Reilly's. It took a little longer to change out because the original was seized in place, broke off, and had to be carefully chiseled out.

Bummer, after new crankshaft position sensor it runs well when running, but the starting problem remains when hot.
I have done all harness checks with VOM as described in the service manual, everything checks out okay. I have voltages everywhere I should.
So, I am back to searching for a Univeral Electronic Spark Control for the engine.

When I find one and get it installed, I'll post my results.
Thanks again for all suggestions.

 

[Delmer]

Any chance there's any other names or numbers on said "universal spark control" ? Maybe it was made by somebody else and easier to find with other numbers.

 

[DavidL]

when the engine is hot and off, spray a bit of ether in the carb intake (remove the rubber inlet hose). If it starts right up, then it doesn't sound like ignition...sounds like no fuel. That's the problem mine has right now.

Check that you have 12 volts at the fuel solenoid at the base of the carb. That also feeds the electric fuel pump. Mine has low voltage when cranking so I will look there next.

 

[CharlieVT]

Gents,
Thanks for continuing replies.
So far I have replaced the coil pack and the crankshaft position sensor.
I have checked voltages to make sure 12volts are at the appropriate connectors to the ESC (electronic spark control) and the fuel shut off solenoid and the anti-diesel solenoid.
I have even put electrical jumpers on to by-pass all the manlift circuitry so as to power the engine electrics directly.
Problem still exists: Once started, it runs normally, but when hot, doesn't want to re-start. Leaving the key on after shut down will make re-start more likely.
I am back to thinking I need to replace the ESC.
I removed the ESC and cleaned it off and found the label for a part number:
F8JL-12A297-AA, date code 3467, Lot 103, serial no 1948.

Searching online, I found this: F8JL-12A297-AB Lrg425 Module Update Kit for Ford at "TruPar". Only Our Price: $1,199.08
Holy Moly, replacement ESCs for cars and trucks are less than $100.
Any suggestions on other sources for this ESC?

Thanks again,
Charlie

 

[DavidL]

Did you try starting fluid? That is a free test.

 

[Birken Vogt]

Did you price it out from the vendors in post #7?

 

[CharlieVT]

Thanks guys,
Starting fluid doesn't do it.
I've emailed several companies for availabilty and cost, no replies so far.
I'll start making phone calls. Some businesses reply to email really quick but I'm finding that these industrial outfits don't work that way.
There have to be thousands of these Ford LRG-425 (153 CID) engines out there. I'm surprised finding parts is as hard as it is...
I'm just asking here in case someone has been through this process and has a source that "hooked 'em up".
Thanks again, Charlie

 

[Birken Vogt]

I always call Powertech on the phone. They still print carbon copy invoices with a dot matrix printer and ship to me COD where it takes like a month for my check to clear because they do not deal with credit cards. They do respond to email but it's always best to pick up the phone first.

 

[CharlieVT]

Did you price it out from the vendors in post #7?

Yes, thanks for the names of those suppliers.
I now have parts ordered from Powertech, they were the low cost leader and had parts in stock.
It turns out that this ESC module is replaced by three separate parts, an ignition control module, a map sensor, and adaptor cable.
The "adaptor" cable (also called a jumper harness by one supplier) alone is priced from $350 to $551 depending on source. Silly me, I was thinking I'd find this thing from an auto parts supplier for less than $100.

Thanks again to all who offered suggestions. I'll post again to let the group know the outcome.

 

[DavidL]

A map sensor? I thought you had a carburetor? Map sensors are for EFI engines....

 

[Birken Vogt]

MAP sensor on these is for adjusting ignition timing depending on load.

 

[CharlieVT]

New
Quote DavidL: "A map sensor? I thought you had a carburetor? Map sensors are for EFI engines.... "

Yeah, when I saw that I was confused. But more than one supplier gave me the same three replacement items for the original part number I had from the existing ESC installed on the unit.

I did a little research and learned that some carburated engines also have a map sensor installed in the intake manifold. I too had never heard of them except in fuel injected engines.

When I get the replacement parts next week, I'll take some pictures and see if I can post 'em here in case it would be of help to anyone else.

Thanks again for all the replies.