I have been having issues with a 1996 f250 5.8 when starting my truck when it is hot outside. It will struggle to start and blow black smoke out when it finally starts. When the truck is cool or cold it starts like a champ. Battery is good all grounds are in good shape. Truck has 55,000 miles on it and all parts appear to be original. So only makes since that parts are going bad.
I have ran a tester and no trouble codes have been stored.
I have read that this could be a multitude of things. TFI module - Ignition Module - PIP sensor - Coolant sensor - fuel pressure regulator.
There are so many threads and ideas on this, it is hard to narrow down where to start.
This is not my daily driver but I do drive it at least twice a week and on weekends to go fishing.
Any help would be greatly appreciated


I have changed distractor cap, rotor, plugs, wires, fuel filter, changed coolant, thermostat. All ford parts. Not because of this issue but just to get the old out with some new.

 

You should tell us what truck you have, what engine, what trans, etc.

 

Sorry about that. I got in a rush.
It is a 1996 F250 xlt single cab two wheel drive 5.8.
I have added this to the first post.

 

Black smoke is too much fuel. You should check your fuel pressure regulator first.

You said 2 different things - you said hard to start when hot outside, but then you said when the truck is cool or cold it starts fine.

Which is the controlling factor? Ambient temp? Or engine temp?

 

I would say both. Yesterday I drove to work and it started fine with ambient temp around 45. But 9 hours later when I started it to go home temp was around 80. It had a hard time starting.
Sunday I went fishing and parked in a nice shaded area ambient was around 75 and after two hours it was hard to start.

 

What is the best way to test a pressure regulator?
I see that removing the vacuum line and see if fuel is in the line is one way to test. Connecting a gauge to the Schrader valve and testing the pressure when on and off is another way? See is pressure drops fast or slow.
Would a leaking injector cause a hot start problem? Or would an injector leaking cause problems hot or cold?
Thanks for the replies.

 

The term "hot start" would be attributed to engines over 140 degrees, so the EEC will be looking at factors like fuel, crank time, and timing differently than a "cold start".

There ARE a ton of threads on this.

In your case, 9 hrs., being really a cold start, even though the ambient temperature is somewhat warm, would seem to have more to do with a recently pressurized fuel rail.

That seems to go with your theory on a fuel issue.

Follow the procedure for KOEO pressure tests, and KOER pressure tests.

A rebuild or replace of injectors is very possible, fuel pressure regulator can be replaced while the fuel rail is off.

 

TobaccoBarn,


I really appreciate the help. When you talk about the KOEO/KOER pressure tests. Do you mean attach a pressure gauge to the Schrader valve and watch the pressure for both tests? A drop in pressure with the KOEO test would indicate a bad injector/injectors? A drop in pressure with the KOER test would indicate a bad fuel pressure regulator? Issue continues with either tank, so I don't think the pumps are the issue.
I have ran test with the ODB tester and no fault codes appear on the KOEO/KOER tests. Would a bad injector show a code? In the past I was able to put a long screw driver against an injector and put my ear up against the screw driver. You can hear it open and close (ticking). Would this maybe work to see if an injector is malfunctioning? Or is there a better way to see if an injector is bad with out having to remove it?


I hate to keep asking all these questions, but I don't want to throw money at something without at least a good idea of what I am getting into.


I really appreciate all the help and I want to keep this truck going for many more years. She looks to good to give up on her.

 

I suspect leaking injector(s).

 

If it is a bad injector(s), why would it start perfectly when it sits over night?
I am not questioning the answer I am just curious as to why that is the case.
During the winter when I drive to work it starts perfect in the morning and in the evening going home. Now that the ambient temp is on the rise the issue begins.
If I pull the injectors can I connect them to a 12volt source and see if they are working correctly? Or do I need to bring them to a service center?

 

A leaking injector in and of itself would not set a code.

You'll have to conduct tests, and like a lot of things along this line, sometimes you can only rely on your best guesstimate based on process of elimination.

Let's say you drip some fuel into the cylinders and it reacts to some residual heat, the condition that causes an excessive crank time, then over time as metal engine parts shrink back to their smallest dimensions, at say 40 F, fuel leaves cylinders through rings or ?, and you have your next start attempt on a fresh system.

(I might get hit for this)

At the top of this forum, under "tech notes", is an injector rebuild tutorial, but it does not include a bench test.

Get your pressure tests done, follow the factory procedure, collect the data, and map out your next move.

Rebuilt injectors are available on ebay that are advertised to have been bench-tested.

Get the EXACT ones for your application.

Anything you do, for a 20 yr. old digital-controlled, injected truck, is just work out of the way.

A net gain.

 

Because the leaked fuel drains off into the crankcase. It won't drip continually, only until the pressure is relieved on the fuel rail.

 

Thank you both for the info, great stuff.
I might bring it to a shop for a pressure test and see if the injector(S) have failed.
I will change the pressure regulator myself before I bring it to a shop.
Thanks again to everyone for all the help.

 

I am having the exact same issue with my 1995 F150, 5.0L, 4WD. Started last fall, winter no problem, first 80 degree day this spring problem back again.

Same recommendations apply to the 5.0 as presented here?

 

I would assume so.
I watch this TV show called Wheeler Dealers on the Velocity channel. In one of the shows the mechanic used this system to clean the carbon out of a car, injectors included. It appeared to work very well.
Does anyone know if there is a way to clean the injectors (professionally) without having to remove the injectors? I don't mind paying a bit more if I don't have to remove the injectors.