FZJ78 diesel hard start ?

[barnstormer]

I'm down here in Haiti helping manage a hospital, and we've got a 2001 FZJ78 Troopie that just won't start reliably. Here's the situation:

It's a 1HZ non-turbo diesel

There is power to the fuel solenoid
There is 12v to the glow plugs
It will crank and crank and not start, but with even the tiniest of pushes in gear it lights right up and runs fine. Once running it has no issues.

I've tried jumping the fuel solenoid to the battery, no change
I've tried jumping the glow plugs to the battery, no change.

It's a good thing there are plenty of hills around to park on, as it will start easily with just a bit of rolling, while it will basically never start using the starter.

It seems like the starter spins the engine at a reasonable speed.
I've swapped in a new battery to see if that would help (no), although the batteries here are pretty crappy.


My guess is this: when the starter is cranking, the voltage to the solenoid is too low to hold it open, but when it gets a little "oomph" from the rolling, the load on the starter goes down, the solenoid opens, and the engine starts.

It's quite warm here (80*+) and it doesn't seem to matter if the truck is cold (first start of the day) or warm.


Any other comments? It's kind of driving me nutty.
Thanks!

 

[musicmaan]

wow, sounds like a real pain in the butt.. I can't fix it from here, but I'll tell you what you can do, go ahead an ship that 78 Troopie to me, I'll have a look see, and I, ummmmm, promise I'll send it back

 

[kerry]

If your hypothesis is correct, it should start if you put 12v to the fuel solenoid from a separate battery while trying to start with the vehicle battery. If it starts under those conditions, you could then brainstorm about how to start it.

I'm confused on one point: are you using the starter when push starting it?

 

[barnstormer]

Sometimes when I'm alone with it I use the starter to get it rolling (even on a hill, because it's not smooth pavement, but rather rocky ground). Once it's moving with gravity at all, with the starter engaged or not, it will start quickly.

 

[oonimog]

I've found that if the battery or starter is weak and the engine spins slowly, they never start. Bump starting it may be spinning the engine over faster.

 

[kerry]

There is one difference between the two ways of starting: the key is in the start position or the run position. Maybe power to the fuel solenoid is being lost in the 'start' position and maintained in the 'run' position. Have you checked that the fuel solenoid is energized with the starter turning? It may not be a problem with the battery but a problem with the ignition switch.

 

[barnstormer]

There is one difference between the two ways of starting: the key is in the start position or the run position. Maybe power to the fuel solenoid is being lost in the 'start' position and maintained in the 'run' position. Have you checked that the fuel solenoid is energized with the starter turning? It may not be a problem with the battery but a problem with the ignition switch.

Wouldn't this problem (if it existed) be at least temporarily overcome by the jumping of the solenoid to the battery during starting?

 

[kerry]

Wouldn't this problem (if it existed) be at least temporarily overcome by the jumping of the solenoid to the battery during starting?

Yes, it should.

 

[MoGas]

If your hypothesis is correct, it should start if you put 12v to the fuel solenoid from a separate battery while trying to start with the vehicle battery.

Exactly the direction I was going to suggest you go. I also would ask if it had been run out of fuel prior to this issue developed. Does the fuel level ever get to a quarter tank?

If the condition persists when you are using a separate power source on the solenoid, I would then do a fuel pressure test. I'm thinking that the fuel pump may be weak.


Dave

 

[kerry]

Does the engine have a primer pump? If so, I'd try pumping the daylights out of it before attempting a start.
When it starts when rolling, does it start at about the same rpm's as when the starter is turning it or does it have to come up to higher rpm's before it fires off?

 

[roscoFJ73]

If your hypothesis is correct, it should start if you put 12v to the fuel solenoid from a separate battery while trying to start with the vehicle battery. If it starts under those conditions, you could then brainstorm about how to start it.

I'm confused on one point: are you using the starter when push starting it?

This what I would do just to isolate the problem,although it really doesnt take much battery power to activate the solenoid.
Ive seen them work when the battery is so dead it wont turn the starter.

By the way,it is a HZJ78 because it has the 1HZ.
An FZJ** has the 1FZ petrol engine

 

[Gifu]

sometimes you need to start simple... check to make sure the battery cables are all tight and clean, and make sure the engine has a good ground. It could be that there's just enough resistance from a bad connection that when the starter is engaged the voltage is dropping to the fuel solenoid.

 

[barnstormer]

So, I spent a while removing and cleaning every electrical connection I could find and it has improved the situation significantly. I wouldn't say it's 100%, but it's much better. Measuring the voltage at the fuel solenoid while cranking the engine, it was dropping to below 10v. Now it's 11.5, (both tested with the engine and everything cold) which is making it start much better (both from starter speed and keeping the solenoid open).

I should really replace the battery cables and probably disassemble and clean the contacts in the starter solenoid, as well.

Thanks for the good advice.

 

[kerry]

Glad to hear that it's working better. One thing to keep in mind: I have a CAT 3208 in my Wanderlodge and owners have reported power problems with the engine when voltage drops to the fuel cut off solenoid. So if you're only getting 11.5 with the engine running, you may also be getting reduced fuel flow which might reduce power.

 

[barnstormer]

When the engine is running, I've got 13.8v at the battery (it's when cranking that I was having such low voltage, from lots of resistance in the loom and starter, I'm guessing)