Hey everybody,my name is Travis call me T I need a little help,I did look through the posts and didnt find anything quite like my problem.
I have a 96 ExCab 2wd F-150 with Auto and 4.9 I6. When its cold it starts fine,if you can be cold in 100 deg heat. I can drive it for a few mins and when I go to restart it miss fires badly for 5 or 6 seconds then runs fine or wont start.
If it sits more than 30 min it"usually"starts fine. The problem is getting worse,may have something to do with the heat? The only way I have found to start it in this condition is to press the accelerator. It has FI so I know that aint right, but its a last resort to being stranded.
The truck has 2 fuel tanks and I know the by-pass valve on return line is busted. It returns fuel to the front tank only. The front tank is the one being used when the problem happens. I honestly have not tryed a hot start on the rear tank but I will tommorow. Plugs,wires and cap are in good shape.
I just dont understand why "If" it starts, it runs fine after a few seconds.Sorry for the long read any help/suggestions would be helpful.
Thanks...T
P.S. this is my daily driver,the one with A/C. The A/C on my 85 Mustang GT is busted.

 

Honestly, it sounds like a classic case of a dirty/bad/cracked/leaky injector(s). When you shut off the engine, the fuel rail and injectors are pressurized, if one (or more) injectors are leaking internally, the engine will "flood" as fuel will drip into the intake. Holding down the throttle pedal to get it started just allows for more air to be drawn in, so the overly rich condition can be cleared easier.

First thing I would do, is try some good injector cleaner in the fuel, or have the injectors cleaned at a professional shop. The shop method uses a machine to feed the cleaner into the fuel rail with the fuel pump(s) disabled while the engine is running on the cleaning solution. If this doesn't clear up the issue, then new injectors may be needed.

 

Update...I still have the same problem plus a new one. I dont usually floor the gas=WOT but today I did while going down the road,stupid people riding too close. The check engine light came on so I went to my 3rd auto parts store,I was looking for an Injector service kit.
I had the code read hoping it would start afterward. I found a trick to start it,flip the switch to the rear tank and start without primeing the pump.I guess the air in the line helped,it started on the first try and didnt buck.
The codes were.. .P0420 probable cause, aa1 Cat conv def failure possibly due to 2,3 or 4.
aa2 Engine missfire
aa3 Large Vac leak
aa4 Eng oil leak into exhaust-valve guide seals,piston rings

2nd code...P1443 Definition. Evap can purge valve mech. fault or VNV default cond.
Explanation ECM detected a fuel tank pressure charge greater than a minus 7 inches of H2O in 30 seconds with a purge less than 0.02 lbs per minute.
Probable cause...aa1 Failed Evap pressure sensor
aa2 Blocked hose between purge valve anf FTP sensor
aa3 EVAP purge valve stuck closed
I was out trying to track down a injector kit that contains the filter screens I saw in another post.I have the factory Bosch injectors,are the filters even avalable for them? Anybody got a part # and or a source.
I had no trouble finding O rings,its the other parts that got me blank stares from almost everybody.I even called first and went there to see a pic .Their pics only had O rings and whatever you call those other flat plastic pieces.
Does anyone think these problems are caused by a faulty injector at WOT? I hope so. I dont need anymore problems.
Im planning on doing the work myself because im unemployed.
If I cant get the screens/filters,do you think I can get by with trying to clean the old ones? I was going to tackle this problem tommorow but the screens/filters have me stumped.
Ill try not to ask anymore noob questions,but you know I will. Thanks...T

 

The problems you list are not necessarily caused by the injectors or any of the other problems listed. Each one needs to be addressed as a stand-alone issue.

 

Wasn't the 96 a 4.2 V6?

 

The 4.2 V6 debuted inn the 97 F150. 96 was the last year of the 300 in the F150 and it was a MAF SEFI setup.
regards
rikard

 

fuel pressure needs to be checked. My 94 had the pressure regulator go bad, which ruined the front pump, allowing the back pump to fill the front tank, which filled the charcoal can, and washed the rings with gas, and ruined the cat from too much gas running through the motor. all your codes are saying just that. I changed the regulator, and the front pump. then the cat. I am building up some money to rebuild the motor now. other than low oil pressure, the truck runs great now. good luck

 

OK, knew it was around there but was thinking it was 96, guess that's what I get for thinking..

 

I'd check the fuel pump relay as well.

 

Update...I tracked down a FI service kit with the screens. I have cleaned and rebuilt the injectors.That was the easy part, getting to them was a chore. 1.5 days and some blood sweat and tears,its done. I took it on a road test with a WOT blast and NO CODES or Check Engine Light ! The throttle responce is crisp and the motor has really good pull.
The injectors must have been the problem. While I was cleaning and soaking them,I did the air blast trick. The first time I powered them up to clean them,all but one only had a faint click. After a good cleaning,they clicked alot harder.They must have been pretty gummed up.
Last Question for awhile...How to check timing on this motor? All I have read says to unhook the Vac. Advance from the Distributor and plug it. My EFI motor dont have a Vac.Advance on the distributor. So can I just hook up a timing light and get a true reading? If not, please dumb down you answers for me. I replaced my Distributor a while back and never checked the timing.It runs fine,I just want to make sure.
Thanks for your replys and advice...T

 

The timing is controlled b the computer, no need to worry about it as it's not adjustable without special procedures, anyway.