I have a 1980 F600 dump truck. It was working fine until an employee changed the spark plug wires. He was a little cold and there are rumors he was drinking a little at the time. Needless to say, the wires were not hooked up properly. The problem I have is this. I want to get the thing running, but I know the engine is not the original in the chassis. How do I figure out what type of engine I have and then the firing order. Also I think I have a problem with the fuel pump. It was wired previously to a 6 volt source. This doesn't sound right to me. I am just trying to fix this thing up to sell it anyway, so maybe one of you guys wants to buy it. If it runs, then everything works fine. We used it to do construction cleanup. PTO is fine.
Any help would be appreciated.

 

Do you have a picture of the engine? If it is a ford Engine the firing order could be on one of the exaust manifolds.

Ford did have a Engine Delete Option on the bigger HD F-series trucks, especially fleet vehicles, so any engine could be in there unfortunatly. Is it Diesel? or Gas?

 

Might also be on the intake.

DT

 

It's a gas engine. I got it started now, but it won't stay running. I hooked the fuel pump up to a 12 volt switched source and used the firing order I found at Autozone for a 351. I didn't realize ford numbered their cylinders from bank then the other. It runs and sounds good initially but then it just peters out when you get off of the gas. It's almost like there is no fuel for idle or enrichment. Maybe Carb rebuild?

 

Could be a timing issue, could be the carb just needs adjustment, could be a pinched fuel line somewhere that's not allowing enough fuel delivery.

I'd wager a guess that a truck this heavy has something more akin to an industrial block(wider, taller, and runs 4 ring pistons) than a 351.

The firing order on Fords is generally shown on the intake manifold in raised numbering.

It does sound like you have gotten it right, or you'd get an awful lot of backfiring going on on initial start, and it would never stay running.

Pull your number 1 spark plug, rotate the engine until that piston comes up to top dead center(TDC) on compression stroke.(Should hear a hiss comming out of that hole, further verified by plugging it loosely with a finger and feeling it blow past.) Then pull the distributor cap free and verify that the rotor is pointing towards the number 1 wire contact on the cap.(All done without the engine running) Due to the nature and size of these trucks, you may want to employ the help of a couple of buddies...one to push the clutch in(block the wheels thoroughly) and one to turn the engine with the appropriate sized socket and a long breaker bar, while you feel for air movement, and feel for TDC with something like a peice of hay-wire or a stick that can fit down the plug hole without getting pinched. This is called static timing. From there, you can adjust the timing with a timing light, providing you can find the specs.(will still have to verify what engine you have)

The carb is next.

Adjust the idle/air mixture screws all the way in, and then count 2 and 1/2 turns out on each. Hook up a vacuum gauge to an un-used vacuum port on the intake manifold(or install a T connector in one of the vacuum lines) and then start the truck. Turn the screws out(one side at a time) until the highest amount of vacuum available is reached, then turn them in just slightly. The truck should idle fine after this, providing there are no other problems.

 

Yes, Intake Manifold. Sorry had a brain ****.

 

Thanks for all of the help guys. I went out to look, but I don't see any vacuum ports on the intake manifold, only on the carb. I was wondering though if maybe I didn't wire the fuel pump correctly. In my EFI experience there is always a fuel pump relay to keep the fuel pump from drawing to much amperage. The fuel pump power was previously spliced into the wires going to the coil. I measured this voltage at 6 volts and noted the fuel pump required 12 v. I wired it to a 12v switched source, with no relay.


The question I have is, how come the truck used to run with the 6 volt source and how come the coils fire with a 6 volt source? Like I said this thing's wiring is seriously hacked. Maybe I should trace all of the electrical wires and rewire it?

 

The lack of voltage might be an indication that there is another problem somewhere. Heavy trucks like this often use circuit breakers, as well as fuses(two different locations). The truck is definitely 12 volt, and the only way to reduce the voltage would be to install voltage converters. I would lean towards checking that all battery cables are in good shape, as are all ground connections, and all plug in connections. If there's even a minute amount of "green disease" throughout the truck, the resistance of electrical transfer can deminish as it travels on down the line. Check voltage at the battery, as well, and see where it's at, both engine off and running(if it'll stay running long enough). Let us know what you find.

 

The coil only needs ~8 volts, the fuel pump however may require more.. Is it an in tank pump? It almost sounds like you have 2 wires crossed. I did this once on my malibu. It would idle fine, and ran great with no load, but drop it in gear and bam it would die. In 1980 it's going to have a 370, 429, or 460 in it more than likely. I would also think that is has a mechanical fuel pump bolted to the block or front cover (behind the water pump on the passenger side). The firing order should be (1 5 4 2 6 3 7 8).

 

it should have a 370 lima engine.

 

It's the 370 engine. I don't see any mechanical fuel pump anywhere. The electric pump is mounted on the frame rail and the only fuel lines coming from the tank go to the fuel filter/pump and then the carb. I thought that this was strange because I thought most carbs operate with mechanical pumps. Anyway, the battery is good, but the voltage at the coil never reaches 8v. I don't know if the previous owner bypassed a bunch of stuff just to get it running. I do know that a few months ago, it was running fine and then a worker changed the spark plug wires and then it stopped.

 

I don't know what the employee did, but you might want to check the wires running to the coil. I know it sounds stupid, but its normally silly little things like this that keep the trucks from running. When I tuned up my truck, my friend who was "helping" accidentally pulled the cap off the coil and never pushed it back on all the way. To make a long story short, 3 days later and a lot of head scratching, my foot accidentally kicked the coil and the cap fell off. Pushed it back on all the way and the truck started right up. Also just double check to make sure he put the wires on all the way. Good luck.
Mike