Fuel not getting to the engine

[Rgdl]

I'm trying to diagnose why my M818 won't start. The batteries (when charged) turn the engine over fine, but it seems fuel is not getting to the engine. I checked the emergency stop cable (the most likely culprit) and it's not the problem.

I still haven't pressure tested to check the lines for leaks. What method do you guys use when doing this? Is it a simple matter of removing the fuel filler cap and blowing compressed air into the tank?

Short of finding a leak at a hose connection, is it possible that the fuel selector valve has failed?

Is the fuel pump in the engine bay the only means of getting fuel to the engine, or are there secondary pumps in the tanks?

 

[doghead]

When did it last start?

The IP pump draws fuel up from the tanks(no in tank pumps)

Tank selector valves are know to be a source of air leak, causing starting and idling issues. So is the fuel filter bolt(seal).

Old dry lines are a problem with these trucks also.


You can prime the fuel system with the hand pump on the dash. Open the petcock on the air intake elbow, and pump untill its solid fuel.(directions are in the -20 TM).

 

[Rgdl]

When did it last start?

I last drove it about three weeks ago.

The IP pump draws fuel up from the tanks(no in tank pumps)

Tank selector valves are know to be a source of air leak, causing starting and idling issues. So is the fuel filter bolt(seal).

Old dry lines are a problem with these trucks also.

These items are why I need to pressure test the system. But even if these had some leakage, wouldn't I still get some fuel. The engine might run rough but it should still run no?

You can prime the fuel system with the hand pump on the dash. Open the petcock on the air intake elbow, and pump untill its solid fuel.(directions are in the -20 TM).

Thank you. I will read up on this TM.

 

[73m819]

no wont start if the pump is drawing air, once started , will run rough

 

[drgreg]

They can be real cold blooded beasts if you have any fuel system leaks. I remember something about the electric solenoid also, I will try to find the thread later.

 

[Rgdl]

How do you guys recommend I pressure test the fuel lines? Can I just open the tank and blow compressed air into it? Do I need to seal the filler hole with tape as I do this?

 

[WillWagner]

Another thing to look at is the manual shut off. If you used that to shut the engine off last, you'll need to manually go flip the lever back on. It is located at the outlet line off of the pump.

 

[m1010plowboy]

The $10,000.00 dollar leaf, a fly and a seed

I'll tell you a story of a 10G leaf.

An associate told me of a friend of his that had an expensive truck. One day the motor starved itself of fuel. After some time sitting waiting for a tow truck, the truck started and ran fine for a few days.

This went on for several months of fuel pumps, filters, injector pump re-builds, lift pumps etc. until one day after investing $10,000.00 in trouble shooting, they decided to pull the tank.

What they found was a big ol' poplar leaf in the tank that would float around until it got close enough to the suction of the pump and plug it completely or partially until the truck was shut off. The leaf would then, at it's convenience, float away until the circumstances let it happen over and over again.

A Fly and a seed:

I'm lucky enough to own a few diesel toys and yesterday while one of the best operators I know was flying my new TEREX PT 70 track machine she thought she ran it out of fuel.

After re-fueling and bleeding.......both the fuel system and my arms from hard to reach injectors.... we could not get steady fuel to the injector pump.

Frustrated after 5 hrs of trouble shooting and smelling of diesel perfume, I had the dealer provide me with a complete fuel filter assembly. As I removed the original assembly, stuck inside the filter housing was a large diesel soaked blue fly and some type of 1/4" diameter seed. Just large enough to plug the line to the pump and not get sucked into it.

The Terex has a macro screen in the fill spout that has never come off so the fly and the seed was "manufactured" either in the tank or below the fill spout of this unit and at some point broke loose just in time to mess with my week.

The moral of the story:

So if you're trouble shooting fuel........sometimes it's best to start at the source. Eliminate the tank as the problem first...not last.

Run a secondary line to a jerry can and start shooting.

If you get some pics of the system I'm sure someone will tell you where pumps, filters and solutions may be.

Good luck and let me know how things got solved. I hope it's as easy and cheap to repair.......as these were.

 

[Rgdl]

Another thing to look at is the manual shut off. If you used that to shut the engine off last, you'll need to manually go flip the lever back on. It is located at the outlet line off of the pump.

Thank you Will. That was the first thing I checked. I didn't want to get flamed by the SS members for overlooking the obvious.

 

[Rgdl]

I'll tell you a story of a 10G leaf.

An associate told me of a friend of his that had an expensive truck. One day the motor starved itself of fuel. After some time sitting waiting for a tow truck, the truck started and ran fine for a few days.

This went on for several months of fuel pumps, filters, injector pump re-builds, lift pumps etc. until one day after investing $10,000.00 in trouble shooting, they decided to pull the tank.

What they found was a big ol' poplar leaf in the tank that would float around until it got close enough to the suction of the pump and plug it completely or partially until the truck was shut off. The leaf would then, at it's convenience, float away until the circumstances let it happen over and over again.

A Fly and a seed:

I'm lucky enough to own a few diesel toys and yesterday while one of the best operators I know was flying my new TEREX PT 70 track machine she thought she ran it out of fuel.

After re-fueling and bleeding.......both the fuel system and my arms from hard to reach injectors.... we could not get steady fuel to the injector pump.

Frustrated after 5 hrs of trouble shooting and smelling of diesel perfume, I had the dealer provide me with a complete fuel filter assembly. As I removed the original assembly, stuck inside the filter housing was a large diesel soaked blue fly and some type of 1/4" diameter seed. Just large enough to plug the line to the pump and not get sucked into it.

The Terex has a macro screen in the fill spout that has never come off so the fly and the seed was "manufactured" either in the tank or below the fill spout of this unit and at some point broke loose just in time to mess with my week.

The moral of the story:

So if you're trouble shooting fuel........sometimes it's best to start at the source. Eliminate the tank as the problem first...not last.

Run a secondary line to a jerry can and start shooting.

If you get some pics of the system I'm sure someone will tell you where pumps, filters and solutions may be.

Good luck and let me know how things got solved. I hope it's as easy and cheap to repair.......as these were.

Great story.

A friend recently told me one similar about troubleshooting an electrical problem in his house. After spending a lot of frustrating time trying to figure it out, it ended up being a simple loose connection at the switch.

 

[crasheej]

All these trucks need do is suck a little air and you have is a big problem. After replacing all the hoses I've never had any more start problems. The TMs don't cover the hoses. That should be the first place to start.

 

[jasonjc]

Also check the pick up tube in the tank. Mine had a pin hole rusted in it.

 

[Floridianson]

As said replace all hoses on slector and check every connection from tank to TP for tight. Wiggle all copper and if just a little lose back off and retighten. You can also have problems with the line that runs to primer. I live in FL. and put a plug in the TP where fitting is for primer as I don't need it.
The electric shut down would be the only outher place so far I have found to go bad. Screw out with elect screw in to bypass elect.

 

[area52]

All these trucks need do is suck a little air and you have is a big problem. After replacing all the hoses I've never had any more start problems. The TMs don't cover the hoses. That should be the first place to start.

Actually the TM's do cover the fuel hose replacement, I believe its in the -20.

Remove the tool box to gain easy access to the fuel selector valve.

 

[LanceRobson]

It is worth noting that any original rubber part on these trucks is about 40 years old. Changing the rubber fuel lines as soon as you get the truck is the same kind of preventative maintenance as changing the vacuum lines on a CUCV. Cheap and it saves a lot of cursing and head scratching.

Lance

 

[MyothersanM1]

If these trucks suck air you'll be sucking wind. On the dual tank trucks the fuel selector switch is most likely the culprit. But, check all your rubber and fittings.

Two often overlooked rubber items are...say it with me...The Primer Pump O-rings. Brasscraft #0562 3/8"ID (1/2"OD) X 1/16" Wall from Lowes or pretty much any hardware store...

 

[MASIC]

Here is the issue and fix I did for my fuel problem:
When starting my truck I had to have the engine crank over at least 15 revs of the crank before it actually fired up. I went through the whole system piece by piece and found every part in good shape from the tank to the injectors. I mean in pristine shape! But when I reassembled the whole works nothing changed for the better it actually got worse. What I ended up doing was bought fittings and clear hose and jimmy rigged a piece of clear hose from my tank port to the pump suction line, before the filter, after the filter and then just before the pump. I then tried to fill the fuel line right at the last fitting just before the fuel pump. Obviously I was just filling the tank from this suction line so I scraped this idea. I then pressurized the fuel tank with compressed air by jamming a rag at the tank filler port and a air nozzle. I had the fitting at the injection pump just loose enough to let the air purge until the fuel made it to the pump. Once the fuel was there I tightened the fitting and shut off my air. Cranked the engine over and it fired right up almost instantly. I ran it for ½ hour while watching the fuel in the clear hose sections. I saw absolutely nothing! So it turned the truck off and lit a smoke and just after a few drags of my cig I started to see air in the clear hose just before the injection pump. I watched this area carefully to see if the air was coming from the filter side of this clear hose. Once again I saw nothing!
I do know at this point that I had issues with the injection pump side of my clear hose. I cracked the line at the injection pump and had the fuel drain back to the tank. I then began to take the pump apart at every port that I could on the pump and what I found was a small crack in the filter screen plug that goes to the bottom of the injector pump. I decided to fix this plug with some crazy glue just to try and see if this was the issue. I reassembled everything and purged the air from the line again. Ran it for ½ hour and then turned the engine off, lit a smoke took a couple of drags and found no air. I let the truck sit for a couple of hours and still no air. I let it sit overnight and still no air. In the end I ended up putting the whole circuit back together along with a brass swing check valve at the fuel filter to keep the fuel from draining back to tank. The truck has never started rough again, see my video .
http://www.youtube.com/watch?v=SsZCcfgMq-k
I did replace my injector pump with a new one I had kicking around and never looked back.

 

[crasheej]

Yes the 20 cover the replacement of the hoses' But no place in the trouble shooting dose it cover them as being , or could they be a problem . MASIC nice looking truck, but I think you need one more upgrade. Your hand grenade is out of date.

 

[crasheej]

I also see that one of the first thing every one goes after first is the selector valve if these were schuh a big problem then they would not be used on your gas line going into your house. The only thing to go bad is the spring on the bottom. I worked on these trucks while in army and air force and the biggest problem was the hoses once in a while it was a brass fitting that some one got a little heavy handed with.

 

[Rgdl]

Thanks for all the help guys. I haven't had a chance to get to the truck but I'm headed out there today.

Just one more quick question: What are the symptoms of a faulty control box. I know these are prone to fail in the Cummins-powered 5-tons. I'm going to try and check the fuel lines first since that is likely the problem based on the majority of opinions, but was curious as to how to tell if the control box is mal-functioning.