I have a 1996 f250 XLT 2wd 351 that I believe has a leaking injector/s. When it is cool/cold outside the truck starts like a champ. When it is warm/hot it is difficult to start at first. Ran scan tool and no codes other than 111 showed. So as you can imagine I have a few questions.
I have seen a few write-ups on removing the injectors and I see different ways to do so. Some say just remove the upper air intake plenum and others say you must remove the intake manifold. Any idea which is correct?
When I pull the injectors can I go one by one and pour fuel in each one. Will it leak if it is a leaking injector or must there be pressure behind it?
Is it worth trying to clean/rebuild them?
If money is not to much of an issue should I buy new? (Not that I want to throw money away)


Thanks in advanced to everyone.

 

What do your plugs look like? Wet? Does the fuel pressure hold with the pump off?

 

Here is a primer that has a good deal of info:

https://www.ford-trucks.com/forums/1...to-thread.html

I've done mine using a spare injector plug (not 100% necessary, small spade lugs will work)



And another thread, possibly better:

https://www.ford-trucks.com/forums/1...d-install.html

 

Hardscrabble. I probably should get that checked before removing all the stuff. A leak down test? Any idea what the pressure should hold after shutoff? Also the injectors look fine on the outside. I am still not sure the best way to remove the injectors.
Scndsin. Thanks for the pic and the links. A lot of good stuff in there.

 

You can't just fill the injector with fuel & see if it leaks. They are like a electronic operated hose nozzle that is normally closed under pressure.

You usually put a fuel pressure gauge on the injector rail & see how long it "holds" pressure.

Running the truck, letting it sit, then pulling the plugs & seeing if gas soaked after a few hours will roughly indicate a leaking injector, but is not always 100%.

Removing the injectors means removing upper intake,

Then 4 bolts holding the fuel injector "rail"...

Then "working" the injectors out of their holes in the manifold (Clean with compressed air & carb cleaner first to keep grit out) & rail.

They are held tight in the rail & manifold only by tension of the O rings.

 

What he said. This is what I mean. There is a fitting on your injector rail to hook up a gauge, it looks like an air conditioning fitting.

When you say leak down test you are usually talking about a cylinder pressure test like a compression test. You can search leak down test and read about it.

Leaky injectors look like flooding.

 

Thanks you both for the info. I will check the fuel pressure and see how long it holds. Once the truck starts, a small amount of black smoke comes out of the exhaust. Too much Fuel burning I would guess. Which leads me to believe leaking injector or bad temp sensor.
Thanks again for the help.

 

I will go and buy a fuel pressure gauge and connect it to the schrader valve, before going any further. I have seen that the 351 should read around 32 PSi while running. Then when turned off Pressure should not drop any more than 5 PSI in a minute. Any idea if that is correct?
Thanks

 

Just rent/borrow (loaner program) at your local big 3-4 parts store.

That number sounds about right, but I'm not 100%, so hopefully somebody will chime in.

I've got a BBK mounted permanent on my rail & it holds some pressure for days. (Drove it last Tuesday, still has 12 lbs today)

 

I guess if I drop pressure in a day or sooner then a leaking injector/s?
Thanks for the info.

 

Well, one thing we never had you do was pull vac line off regulator & see if its full of gas... Sorry, old guy brain fart.

 

I have a book that stated 1psi drop every 30 seconds for what it's worth...

 

I have recently changed the fuel filter and the regulator in hopes of that fixing the issue. There was no change in hot start issues. I will get a fuel pressure gauge as soon as I can.
If the pressure holds, any ideas what next? What about the starter? I have heard that heat can cause issues with starters. This is an all original 1996 f250 with only 55,000 miles on it. The only thing that has been changed (other than normal maintenance and tune up) is the alternator. Everything else is all original from 1996.

 

I guess you need to elaborate on hot/cold start in regards to time. Are we talking 3-4 seconds crank to run & then 10-15 crank to run or what?

Does the engine labor/drag/ turn slow or does it just not catch?

There's age & then there's mileage. a 96 & 55K is not much unless it was driven into the ground.

I bought my 94/5.8/141K that was somebody's bass boat hauler & commuter truck from Warner Robbins GA.

It had a new parts store starter, cheap oil change house plugs & original wires & a vac leak.

I put in an Optima red top, Motorsport wires, Motorcraft copper plugs & a slightly hotter Mallory coil (no longer available) & a Motorcraft relay, set the timing to 11*-12* and it would start in all temps in under 2-3 seconds.

I later ditched the air pump (with a shorter belt), added a Taurus electric fan & a 4.9 snorkel on the air box & felt like I picked up 25 HP and definitely got a more peppy engine.

 

In the mornings when it is cool or cold, the truck starts up great. In the evenings when it is hot outside it has a hard time starting. Or if it is just 80 Degrees or more it is hard to start. Yesterday I had to crank it three times before it started. Then a puff of black smoke comes out of the exhaust. I don't notice the starter having issues turning but it is hard to tell.
But, why no issues when it is cool outside? Only in the summer times.