94 Mack ch613/E7 won't restart after it gets hot

[Brianpcp]

Title kinda says it all ..... 94 E7 starts fine first thing in the morning, runs good all day. If you don't shut it off.....

Shut it off when it's hot and it won't restart. New lift pump, new filters. Reman injection pump when I bought it(not sure how long ago it was installed) .... Getting fuel spitting out of injector lines when you crack them open. Sometimes it will fire up with a little ether, sometimes it won't... Please help, pulling my hair out!!!

[Joey Mack]

is it V-MacII?  if so, check the condition of the Duetch plug at the injection pump gov. housing..  look for loose terminals and damaged wires..  jojo

[Brianpcp]

1 hour ago, Joey Mack said:

is it V-MacII?  if so, check the condition of the Duetch plug at the injection pump gov. housing..  look for loose terminals and damaged wires..  jojo

That was one of the first things I did..... Seemed a little loose but didn't seem to help...

[Vmac3]

Is the check engine light on? Make sure the injection pump connector is good. I believe there is a ground circuit protection relay beside the wiper motor. Remove the hardware and clean the terminals. There is a module behind the passenger side kick panel. Its black in color right beside a big grey module. If it doesn't start try tapping on the black module. See what happens. Sometimes there is water intrusion and does freak the module out. 

V

[Joey Mack]

I forgot to ask... When you say it doesn't start, do you mean it turns over but doesn't fire?  Jojo

[br549]

on the vmac engine when it would quit running when it was hot and would not restart Mack said to pour a gallon of water on the governor of the fuel pump, if started it was I not sure but I think it was the magnet or sensor in the governor need to be replaced.  I read your engine wont restart after cutting it off but give it a try and see.

[Brianpcp]

2 hours ago, Vmac3 said:

Is the check engine light on? Make sure the injection pump connector is good. I believe there is a ground circuit protection relay beside the wiper motor. Remove the hardware and clean the terminals. There is a module behind the passenger side kick panel. Its black in color right beside a big grey module. If it doesn't start try tapping on the black module. See what happens. Sometimes there is water intrusion and does freak the module out. 

V

It was on intermittently  (3-5 or 35 however you want to say it), we tracked down that the notorious small brittle hose that comes from the pump back up to the head was cracked, repaired, and the "lift" fuel pump was bad...,replaced that..... We have not had the light on since(obviously except at initial key on) it runs and pulls alot better , starts right up(90% of the time when cold), but will not restart when hot.....

[Brianpcp]

1 hour ago, Joey Mack said:

I forgot to ask... When you say it doesn't start, do you mean it turns over but doesn't fire?  Jojo

Correct.... I cracked the lines on the injection pump it is getting fuel(although it doesn't seem like a lot in my opinion as in it doesn't seem like a lot of pressure but this is my first round of messing with a an old Mack so I don't know what to really expect)

[Brianpcp]

2 hours ago, Vmac3 said:

Is the check engine light on? Make sure the injection pump connector is good. I believe there is a ground circuit protection relay beside the wiper motor. Remove the hardware and clean the terminals. There is a module behind the passenger side kick panel. Its black in color right beside a big grey module. If it doesn't start try tapping on the black module. See what happens. Sometimes there is water intrusion and does freak the module out. 

V

One of my next steps I to double check and clean all wiring connections... Thanks

[Brianpcp]

14 minutes ago, br549 said:

on the vmac engine when it would quit running when it was hot and would not restart Mack said to pour a gallon of water on the governor of the fuel pump, if started it was I not sure but I think it was the magnet or sensor in the governor need to be replaced.  I read your engine wont restart after cutting it off but give it a try and see.

I'll definitely give it a go and see what happens 

[Joey Mack]

You say when you crack the fuel lines when its hot, that the fuel pressure seems weak. Is that correct?   I wonder if something in the fuel shut off is failing?  I wish I knew what the inside of that pump looked like.  I never messed with them on the inside..  I wonder if you tapped on the Gov. Housing, lightly with a small dead blow hammer while some cranked it over, if it would knock somethin loose, and fire up?   Jojo

[Brianpcp]

12 minutes ago, Joey Mack said:

You say when you crack the fuel lines when its hot, that the fuel pressure seems weak. Is that correct?   I wonder if something in the fuel shut off is failing?  I wish I knew what the inside of that pump looked like.  I never messed with them on the inside..  I wonder if you tapped on the Gov. Housing, lightly with a small dead blow hammer while some cranked it over, if it would knock somethin loose, and fire up?   Jojo

That is correct....I may try that too.... Didn't have much time to mess with today, dealing with a Mack triaxle dump that some dummy backed into a pond and another dummy wrapped a chain around the front axle to an excavator to pull it out...... The only thing they managed to pull out was the front axle from under the truck.. makes ya wonder how some peoples thought process(or lack there of!!!) works.....

[Joey Mack]

Have you tried adding Stanadyn to the fuel filters and tanks to see if it can loosen up the Inj. pump guts?  

 

Yeah its hard to feel how hard you are pulling in an excavator, but I would figure the guy on the ground would be watching...   I guess watching the axle come out..   

[mechohaulic]

opinion from an ole man based on simpler times. !-engine turns over =fuel pressure at line lower; is the engine turning over just as fast when hot as it does when it first started cold?? should the engine have a "weak "starter when hot turns engine over slower, results COULD be lower fuel pressure at injector lines.  common sense would notice slower turning engine ; but common sense would also say :: DON'T hook a chain to front axle! just sayin. trying to cover all bases. 

[mechohaulic]

what do these NEW engines use for fuel shutoff? obviously it's not mechanical  ; electronic controlled solenoid over fuel? others like cummins have(had) the fuel solenoid opens and closes for fuel. possible fuel pressure some where greater than solenoid can over ride ? reading all responses regarding wiring , don't see where bad wires would make a difference hot or cold .a relay or module ; yes . hope this topic has positive results ; i'm always eager to learn new.

[BOBWhite]

I've got a few diesels that sometimes act like this. Vaperlock is the best way I would describe it, only that can't really happen on a diesel. In all of them Ive seen there seems to always be a problem with the fuel line or air getting into the fuel somehow.

Try clear line between the fuel filters and injection pump and look for bubbles if you get desperate. One of the trickiest problems to diagnose on a diesel. 

Best of luck

[Brianpcp]

10 hours ago, mechohaulic said:

opinion from an ole man based on simpler times. !-engine turns over =fuel pressure at line lower; is the engine turning over just as fast when hot as it does when it first started cold?? should the engine have a "weak "starter when hot turns engine over slower, results COULD be lower fuel pressure at injector lines.  common sense would notice slower turning engine ; but common sense would also say :: DON'T hook a chain to front axle! just sayin. trying to cover all bases. 

I thought about that too but it spins just as fast.... I even went one step further and hooked jumpers to it (even though it was spinning fast) just to see .... I thought maybe weak batteries or a bad starter might be dragging voltage down enough to starve or mess with relays, injection pump, solenoids, etc but no difference.... Voltage drops down to about 11.5 - 11.9 when spinning the starter (without jumpers hooked up) but stays up about 12 - 12.5 with jumpers "helping"

As far as chain to axle ... thats one of my uncles trucks and two of his employees..... I would've fired them on the spot.... 1st problem is they weren't even supposed to be using the truck 2nd problem is they were too lazy to get a chain or choker that fit in the clevis on the truck(chain was 150' away) so they used the big chain we keep on the excavator..... 3rd (and biggest problem) I am 99% confident that alcohol and some other substances were in play..... I wouldn't keep employees like those!