My truck is a 94 F-250 7.3L IDI Factory Turbo, 5 Speed manual no mods. Engine rebuilt around 4,000 miles ago. (She had 202,000 miles and #1 cylinder rings gave way)

For the first 3,000 miles after the rebuilt it started first time every time, Fast. It has progressively gotten harder to start. This happens first start of the day or after sitting 15 minutes or more (if I shut it off and right back on, she starts like a new one).

It cranks over several times and acts like a flooded gaser, then it will start with a good puff of black smoke followed by a stream of white smoke and idle rough for up to a minute, some times the idle smoothes out with in a few seconds.

It runs great and idles fine once it gets running. She blows a little black smoke on shifts, other than that no smoke. I suspect the smoke at shifts is normal, but it did not do it the first 3,000 miles after the rebuild.

I have checked the entire glow plug system (Wires, plugs, controller) using procedures in a haynes manual. It checks out fine. Batteries load test great! Starter amp draw is 345amps.

I have read several post on this subject and plan to go through the fuel system in a systematic way. I am just hoping specific details of my problem will help some one pin point the most likely cause. (I just don't want to hear IP failure is on the horizon. )

Thanks for all the great information posted here. As a new Smoke Blower this sight has taught me a lot and I am greatfull to all.

 

The way you describe it it sure sounds like your have a air intrusion problem somewhere in your fuel system.

As the truck cools down the fuel lines going back to the tanks usually have a bit of vacuum on them as the level of fuel in the tank is lower than the engine. If any of the lines at the connections are not tight then they can let air into the lines which will require a lot of cranking to get it cleared before the engine will fire up.

There is usually not enough time for air to get into the fuel lines between warm starts so she will fire right up.

The rough idle for up to a minute is what is takes for all the injection lines to clear up any air. Until all the air is gone from all the injections lines the truck will idle rough or may even stall.

Check your fuel filter make sure it is tight. Start going over all your fuel return line connections on top of the injectors. Make sure the clamps are thight, make sure all rubber hoses and rubber orings under the return caps are soft and new.

It might take you a while to find the air leak. It can be very frustrating.

Running full tanks helps as it minimizes the vacuum in the fuel lines as the truck sits and cools.

I don't think you IP is going, sound more like classical air intrusion to me.

 

Hamberger, that is what I am hoping for. I am going to replace all the hoses and injector "O" rings and check valves this weekend. It was the smoke and rough idle that had me scared, but it makes since the air has to clear the lines before she'll smooth out. Thanks! I will let ya know how it goes.

 

how many miles are on your ip and injectors

 

I am not really sure about milage on injectors or pump. The truck was given to me with #1 cylinder blown. It had 202,000 when I had the motor rebuilt. I think the previous owner had some work done to either IP or injectors or both, but found out it had bad rings.

 

I heard a similar story about bad rings from a guy I bought some factory tire rims from a few years back. He said Ford paid for a complete ring job under warranty. The guy did not have a lot of good things to say about his Ford Diesel.

There must have been a problem with some of the earlier 7.3l who had bad rings.

Seb...

 

Ok, here is an update on my hard start problem. I have replaced all injector "O" rings and new lines and clamps. Changed fuel filter, all is tight there. All check valves seemed to be working (by blowing into line) A visual inspection of lines from engine back to tanks looked good.

I bypassed the mechanical lift pump with an electric capable of 5-10psi and 30gph. I thought this would help save on cranking time. NO LUCK. I still have the same problem.

Yesterday I drove the truck about an hour and pulled into the lot. I shut her down, but left the key on to keep the fuel pump running thinking this would tell me something about my problem. I sat for 25 minutes this way and tried to start her up with the same long crank time. This confuses me. My thought was, keep the fuel pushing through the lines back to the tank, no air can get in. Is this right? Could the high pressure side still be getting air? I don't know where I should concentrate next.

 

Not all starting problems are caused by air.

Sometimes an internal fault in the injection pump could cause poor starting. (Leaking advance valve?, historic dirt in the IP?, All it takes is for a small piece of metal or a paint chip to have gone into the IP during say a fuel filter change)

Since you have eliminated the possibility for air, I would say your problem is most likely IP related.


Seb.....

 

What about trying the trick of pouring cool water on the IP before trying the restart.. I have read on here that you can do that to help troubleshoot a failing IP... I've never tried it but I am having the same issues as Gumboluvr with one of my 88's. I have changed everything. Still the same issues. Does anyone know if this water trick works... If so... what exactly does it help determine. ie: what in the world would water do besides work as a cooling agent?

 

bigblu78,
As I understand it the water's only fucntion is to cool the pump. Even though my syptoms showed up hot or cold, I still tried the water thing with no effect. Good luck with your problem.

I think I have reached the inevitable conclusion Hamberger is correct in saying my IP is dying a slow death. I just wanted confirmation of my logic.

NOW FOR THE NEXT QUESTION I know I should replace injectors and pump at the same time, BUT I am more broke than my truck is right now. What kind of trouble am I in for if I replace the pump now and promise to replace injectors within 6 months?? I really don't have a choice at this point.