A couple of weeks ago I went out to start the truck and it would not fire. I cranked it over several times and it would not hit.

Factors:
-It has set for a couple of weeks without being started ().
-It was the first morning of cool weather (maybe 35*-40*)
-When the weather is cold it normally hits immediately but runs rough for a couple of seconds at cold startup.

I guessed that maybe the fuel pump had bleed down. I hit the prime handle a couple of times and tried it again. It fired immediately but ran rough for a couple of seconds. Since then it has ran and pulled fine. I've drove it several times since then without issue.

So I assume my pump, which might be factory and could have almost 300K on it, is going out. Now my question is should I replace it with a diaphragm style for $40 or upgrade to the plunger style for $150-$200? Truck spec's in my sig...

Thanks for any comments or suggestions.

 

I could easily be just air leaking into the system somewhere allowing the fuel to drain back to the fuel tank.
Could be old fuel lines, bad clamps basically any connection from the injection pump to the sending unit could be the culprit.

 

Thanks for the ideas. If that is true then fuel could be leaking from that location when the engine is running and pressure is built up.

 

If the leak is after the lift pump, it may show a leak.
If it is BEFORE the lift pump, it would be under vacuum when running and there would be no fuel leaking.

You might be able to pressurize the fuel tank with a few PSI of air to pressurize the fuel system to help find leak. Don't go crazy with the air PSI though.

 

With 300K on the motor,and the stock lift pump in place I would want to replace it with a new one....just for piece of mind. But as Oliver said it's more then likely a air leak in the system that is allowing the fuel to drain back.

But it might not even be noticeable, or have a physical drip.....I have a leak at the fuel line connection at the lift pump, the snap/push on fitting. If I clean the motor really well then you can see it's a bit wet around the fitting. But once you get a bit of crud and debris around it it's nigh near impossible to tell.

If my truck sits for more then 2-3 days it might require a couple revolutions of the starter before it will fire.

 

Mine leaks off form a bad o-ring in the fuel heater.

 

Thanks so much for the input.

So to my question of the diaphragm vs. plunger pump... would it just be a waste of money give I don't need to higher output?

 

no. it's a more reliable part. peace of mind is worth it, IMO.

 

I agree with Mr. Fonder.
I went with the kit from The Hungry Diesel. Last year they ran a Black Friday special that included the kit, 322 spring, and THD fuel pin for $250 shipped.


Since the IP is cooled by incoming and outgoing (excess) fuel I see the increased volume of fuel as beneficial. The increase from 4psi to 15psi will also help to ensure that you don't starve the IP at WOT.


The install is pretty easy. The biggest PITA is cutting away the sound deadener material from the tappet cover. I believe there us a write up in the sticky on it.


The only potential negative that I've heard of is that the increased pressure can push the front shaft seal out of the IP. I don't know of anyone who has experienced this.

 

Thanks a bunch for the info guys. You've convinced me.

 

It has long been said that the IP's input shaft seal is prone to pushing out with over 20psig. I've ran 20psig for a few years with no issue. Your mileage may vary.


The custom HVLP (High Volume, Low Pressure) piston lift-pump that THD sells has a 15psig spring and is no threat to our VE injection pumps.

 

For those who've never done a lift-pump replacement, this may be of help . . . .. https://www.dieseltruckresource.com/...install-93722/

 

Good to know. Thanks!

 

Essential on any VE engine in my opinion.

Prevents fuel/oil cross leaking that can happen with a worn out diaphragm pump.

Added bonus - the higher pressure will help a bit with dynamic timing advance.

 

One of most common places for a leak is inj pump, Easy to test, just cup your hand under the pump and see if fingers have fuel on them. Theres a seal in governor that leaks and all fuel runs out of the lines. Its not hard or expensive to fix, you just have pull the pump.