hi,

i have a strange Problem when i start my 1985 6.9.

If it is cold outside around 0 C° i glow it, press throttle half way crank and the engine fires up without any problems, runs for around 5-10 seconds that stumble and die, after that i glow it agin and must crank the Engine a longer time and ist starts hard but then it runs.

If i use the Blockheater it also stumle a little but not died, this happend only at the first start in the Morning after i drive to work (9 mls.) after 8 hours it starts without any Problems ???

Glowplugs are 4 month old Motorcraft, new Fuellines, Tanks cleaned, new Fuelpump ne Filter, i have no idea what happend!

Any Ideas from your side?

Best regards

Torsten

 

sounds like air intrusion to me

 

I don't know why but mine plugged in with air intrusion started fine. not plugged in start stall then a very hard start usually ended up with jump starting it because the batteries died. Mine also has low compression, but I would look for fuel leaks. My final culprit was the fuel heater o ring. I got it to the point it would start fine overnight, let it sit one day without starting It went back to the start stall hard start issue. Best test I found is to let it sit, then bleed the lines using the schrader valve until you have a steady fuel flow. then turn the key. If it starts and runs fine it's air.

 

Air getting to the fuel system. Next time Next time before start, remove the fuel filter, if it is half way empty u have air entering the system.

 

Thank you for your replays,

i will check this, but why did i only have this Problem when it is cold outside and when i not use the Block heater?

best regards

Torsten

 

Probably one of two things:
1. The block heater keeps the sealing O-rings warmer. Warmer rubber will be larger(materials contract when it gets cold). Also, more flexible and less likely to leak.
2. When you have the block heater, it fires up instantly. Maby it has more time to pull new fuel in before running out of what little fuel there is inside the IP.

I do know that I've had one truck do that to me before. If I got it to fire up on the first try, it would stay running. If I didn't, it would have trouble and die and require a lot more cranking to get it to fire up.
Fixing the glow plugs to make it fire right up took care of that for now, but that truck still has an air-in-fuel problem that's going to require pulling the bed and fixing the pickups.

 

Ok Macrobb,

that i can understand

i have no visibel Fuelleaks, so what is the easyest way to check for air intrusion step by step?

best regards

Torsten

 

What Macrob said.

 

Dear Romel,

i have all new Gloplugs, and also new Fuellines

regards

Torsten

 

New does not mean properly sealed.

New does also not mean working properly.

You will want to go over everything again, just to be sure. Test all the glow plugs, time how long it glows initially before starting to cycle on and off.

You say your fuel lines are new. Did you replace everything from the fuel tank to the lift pump?

 

Exactly what Macrobb said. The air can come in in many different places, joints, through pump, filter head, injector return lines. Irelevant if it is new, there still might be air comming in somewhere. My injector caps are moist but starts right away, no problem. Above 10Celsius even without glow plugs. I dont use them unless in winter.

 

You should pull the caps and use some high temp grease to lubricate each O-ring and the inside of the cap. If you use new O-rings and do this, it *will* fix the problem.
If you use the old ones and just add grease, I give it a 70% chance of fixing the problem.

Also, as much as people like saying it, air intrusion is /only/ a problem on the supply side of the system. You could open the return side entirely(pull off a hose, remove a cap etc), and it'll still work... as long as the supply side is sealed.

The problem comes when you have the return line on the fuel filter(which *should* have a check valve in it), OR a leaky filter head, COMBINED with a lift pump which isn't sealing properly.

If you have a check valve anywhere in the supply side of the system, well, it won't drain back. Period.

 

Good Morning,

thank you for your replays, i goes in my mind back to all my repairs (i am new on Diesel) that i do in the time that i build in this replacement Engine.

And now as i read it can also be a Problem with the return lines i remember that the old ones on the Engines was very leaking at first start so i buy a new set of Caps, Seals and lines.

And i had a lot of trouble with this, i use heavy grease as i install them but i need three times to get all of them visible not leaking.

So i think yes this could be the Problem, because for me the returnlines was not in my mind to get air back in the Fuelsystem And maybe my CheckValve (if there is one) is bad!

And now also it makes sense to me that this Problem ist stronger when the Engine is colder, because the Fuelpickups on the Tanks and all Fuellines after the Pump cant show any changing with Blockheater on!

I also will check the new Motorcraft Glowplugs, maybe they have a real short Lifetime

I think i will replace all returnlines and Caps agin (after it is warmer outside).

but where can i buy a realy good set of Caps, seals and lines? i dont like to use the same aging than gives me this trouble!

Best regards

Torsten

 

I just buy the cheapest kit off Ebay. Literally trying to find the worst one.
I have installed 3 or 4 of these so far with perfect results.
F250 F350 7.3L Ford Injector Return Line Kit 1987 - 1994 Diesel TRUCKS NON TURBO | eBay was the latest one I bought.

 

That one ^^^^^ only ships to the US, and Torsten is in Germany. Jan (Romel), since you're reading this thread, do you know of sellers here who would ship to Europe?

Following this thread because my '85 is doing the exact same thing. If I recall, the OEM Stanadyne fuel/water separator is another infamous source of air intrusion, correct? Torsten, do you still have the original water separator? It's on the firewall, driver's side, near the brake booster.