Hello! - Fuel delivery issue with 7.3 IDI

Hello,

Wanted to introduce myself to you guys first, and hope that you accept me into this board!!

I have a 26 ft 1989 International U-haul (7.3 IDI - Spicer 5spd). I've owned this truck for about 10 years now, and bought it outright from u-haul. I use it daily as a company work truck.

I am having a mysterious fuel delivery problem, and I am hoping that somebody may be able to steer me into the right direction.

Several years ago I removed the old plunger fuel pump off the side of the engine, and replaced it with a 5 psi electric pump that starts pumping as soon as the key is turned forward. It has worked flawlessly for the past 6 years, but now every couple of days when I start the truck first thing in the morning, it will run for 4 seconds and then sputter and quit. I can try to restart it and crank and crank until the batteries are dead without even a sputter of hope!

Spraying starting fluid into the cleaner has no effect (after the glow plugs cycle and turn off).

The controller is clicking well, and I have 12 volts in the harness connectors. I have ohmed out all the glow plugs and they test fine when removed (Beru plugs). I have tested them in the block by touching them with a 12v test light. All is fine!

When I take the return hose off the fuel filter, fuel spurts out as the fuel pump pumps. Fuel is trickling back into the fuel tank from the return line, and all hoses and caps were replaced on fuel lines. No leaks!

One the truck starts in the morning it will run great for the whole day.

I am stumped...The fuses to the pump are all good, and I am running new clean fuel.

The shut-off solenoid on the pump has power to it and when you remove the connector terminal it clicks.

Where should I go next guys. I am stumped!!!


Hope someone can help.

When you are cranking and cranking, are you getting any white smoke out of the tailpipe?

And please figure out a way to take power off the glowplugs before using the ether. I know you said it had finished working when you used it, but I don't trust that controller to stay off.

Welcome to the Forum!

To me it sounds kinda like your electric fuel pump is on its way out. What brand of electric pump did you use?

My truck came to me with a Mr. Gasket 5-7 psi electric pump, and I had the exact same issue until the pump finally just quit working period

Thank you for the replies fellas. Yes, there is white smoke coming out of the exhaust. It is very rich smelling. Thanks for the tip about the pump as well! The pump is just an aftermarket "dorman" pump. Cost me a about 50 bucks 7-8 years ago.

That is rather a mystery. The rich smelling white smoke would imply that the injection pump is getting plenty of fuel, and yet the fact that the engine dies after a few seconds tells me, just from my personal experience, that the injection pump isn’t getting fed fuel and is just consuming the fuel that is already in the injection pump, hence why the engine would die after a matter of seconds. The only thing I can think of to explain this is air intrusion. If it is air intrusion, then after white smoke comes out of the tailpipe you should be able to cycle the glow plugs again and get it to fire up. I don’t know if the assumptions I’m making are accurate, but that’s just my two cents

Dane Rickford said:

That is rather a mystery. The rich smelling white smoke would imply that the injection pump is getting plenty of fuel, and yet the fact that the engine dies after a few seconds tells me, just from my personal experience, that the injection pump isn’t getting fed fuel and is just consuming the fuel that is already in the injection pump, hence why the engine would die after a matter of seconds. The only thing I can think of to explain this is air intrusion. If it is air intrusion, then after white smoke comes out of the tailpipe you should be able to cycle the glow plugs again and get it to fire up. I don’t know if the assumptions I’m making are accurate, but that’s just my two cents

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Thanks for your thoughts. I can cycle the glow plugs about twenty times after and crank and crank over again. I had killed the batteries this morning, and then hooked up to a trickle charger. Charging at 20 amps I was able to start the truck after 35 minutes, by putting my foot to the floor and pumping the pedal.

The fact that the engine dies after a couple seconds is a classic sign of a significant air intrusion. OTOH the white smoke out the exhaust would seem to indicate that the cylinders are getting fuel.

Next time you go at it, and the engine dies, pull the fuel filter. Unscrew it carefully and pull it out of the engine area. Try not to spill fuel. If it is only partially full that would indicate an air intrusion somewhere between the filter and the fuel tank. Start by looking for wet spots along the fuel line. Good luck.

When you replaced the lift pump with an electric pump did you leave the old lift pump in place, run the through it but the pressure supplied by the electric pump? If so, check your oil for fuel contamination.

If you can, check the fuel pressure. The electric pump may be getting tired.

That should keep you busy for a bit.

You say your location is PE. Is that PEI?

Two other things, or maybe a couple. When you crank the engine do so for only about 15-20 seconds, and let it rest for a couple minutes. The poor starter is fighting lots of compression. It gets hot. You don't want to burn out the starter.

Also, is the starter spinning the engine fast enough? The engine has to be turning a certain speed (I can't remember how fast) to build up the heat in the cylinders to fire. If it doesn't build up that heat you're just pumping fuel through and out the exhaust. The starter must be in good condition.

gandalf said:

The fact that the engine dies after a couple seconds is a classic sign of a significant air intrusion. OTOH the white smoke out the exhaust would seem to indicate that the cylinders are getting fuel.

Next time you go at it, and the engine dies, pull the fuel filter. Unscrew it carefully and pull it out of the engine area. Try not to spill fuel. If it is only partially full that would indicate an air intrusion somewhere between the filter and the fuel tank. Start by looking for wet spots along the fuel line. Good luck.

When you replaced the lift pump with an electric pump did you leave the old lift pump in place, run the through it but the pressure supplied by the electric pump? If so, check your oil for fuel contamination.

If you can, check the fuel pressure. The electric pump may be getting tired.

That should keep you busy for a bit.

You say your location is PE. Is that PEI?

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Thanks for that. I'll check the filter next time it acts up. I did bypass the old pump all together and put a block off plate on the motor. I do have an extra electric pump here, and I may actually try putting another pump on the truck to see if it helps.

Yes. PEI. Prince Edward Island!

1989 UHAUL said:

Thanks for your thoughts. I can cycle the glow plugs about twenty times after and crank and crank over again. I had killed the batteries this morning, and then hooked up to a trickle charger. Charging at 20 amps I was able to start the truck after 35 minutes, by putting my foot to the floor and pumping the pedal.

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Pretty sure that pumping the pedal doesn't help.

You should push the pedal down once, to let the high idle solenoid kick in. But other than that, while starting, I don't think pumping the pedal makes any difference at all.


My experience...

I have one of those green dorman's as well.

I have been running the truck using only that electric pump, for almost a year.

The truck actually starts and runs, even if I turn that electric pump off!!! But will stall out if I demand too much of it.

With the pump running, it runs and drives normally. But just a bit on the anemic side.

Recently, I decided to leave the electric pump plumbed in and running, bit to add back in, the mechanical pump.

I used two brass wyes, and two check valves, to plumb them in parallel, without either of them being able to back pressure the other.


The difference is phenomenal! It's like I installed a second engine along with the first one.

What I am thinking is that your pump is getting weak. For one. And for another, even though the truck would start and run with that pump, doesn't necessarily mean you were supplying the IP with all the fuel it needs. Now, with it getting weak, it supplies even less.

I am lucky I discovered all this before my IP gave out, because of being forced to run on less supply than it needs. Maybe you have run yours for too long with inadequate supply, and now need a new IP as well???

Bottom line, you could leave the electric in place, and put a new mechanical in as well?

What I like about having both is that I now know the IP is getting enough fuel... But with the electric still being there, I can turn the key on in the morning, and leave it for a minute, to build up pressure in the system, before I try to start it.

Another sign of a failing lift pump is that at high rpms under heavy load the fuel filter light will come on until you back off a little on the rpms

The white smoke is probably due to retarded timing from the low fuel pressure. Replace the pump with a mr gasket 105p or a Holley red and you should be good.

The white smoke means he has fuel. I do not know why it will not fire off on ether. Ether will cover up a lot of sins, like cranking speed too slow, glowplugs not working, etc. But I would definitely disconnect the glowplug system before trying it again. It does work best to give it a good shot right at the aircleaner.

And apparently holding the throttle open some does help starting. It says it right on the sunvisor starting procedure on my truck. Hold it partially down when it's a little cold outside, and almost all the way down when it's really cold outside. That is paraphrasing from memory, I forget what it actually says.

Hey, I dug around and found where I took a picture of the sunvisor instructions. Apparently you are always supposed to hold the pedal halfway.

PC280010 by D Franklin, on Flickr

franklin2 said:

Hey, I dug around and found where I took a picture of the sunvisor instructions. Apparently you are always supposed to hold the pedal halfway.

You must be registered for see images attach

PC280010 by D Franklin, on Flickr

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I was not aware of this info. My truck has not original sun visors.