i have a 93 f150 4x4 with a 357w(yes i know i built the motor). The motor is a fresh build. only parts i reused were accessories and fuel injectors and wiring harness ignition coil and distributor. it has all new plug wires. Motor has 591 miles on it. Cylinder 1 and 3 are missing/flooding. mind you this is a speed density truck it batch fires. I have not had the time to bring home my snap on ethos to check for codes. recently checked them and it said pip signal erratic. not sure if code is still active or not. Truck ran great up until now. its dumping raw fuel out the passenger side exhaust(true duals). It started out as a problem around idle and stop lights. then it started to get worse truck would cut out and lacked power. i replaced the 2 fuel injectors on the missing cylinders thought they were leaking. i have a brand new fpr as i had to crank fuel pressure up to supplement lack of fuel. its only at 55psi. seems like at first i would be fine at higher rpms. also replaced the 2 spark plugs and still no change. maybe pickup coil is boned and it may not be sending a spark to these cylinders. i did try to start the truck up in clear flood mode. accelerator to the floor i roared to life and went up in rpm(thought i blew it up letting it get that high) and it ran good for a few seconds then it went right back to missing/ spitting fuel out the exhaust.

 

Sounds elec to me (pickup coil and PIP), but since it's a fairly new build, she bank fires and we're on the same bank early in the firing order did you run a compression test ?............(may have something mechanical / new afoul)..........since fuel delivery press seems fine (actually above specs), next up is getting some test lights /inductive diagnostics on the injectors/elec to rule out those kind of problems...................also, did you set/reset the timing (with the spout off)?.............

 

tested fuel injectors with noid lights to see if circuit was grounded out keeping the injector stuck open. Fuel injectors are new on those cylinders. and used oscilloscope on injectors to check waveform. waveform looked fine. I have not spark tested the cylinders because i keep forgetting to bring my spark tester home from work. and honestly with all that gas coming out i rather not create any spark outside of the cylinder. lol and as far as any odd noises hard to tell. true dual exhaust running long tube headers. cant hear squat. and valvetrain is noisey due to roller rockers. and aggressive cam so no odd noise there. if it was mechanical it would have to be burnt valves allowing fuel to get past the valve when it is not supposed to. because with batch fire fuel sits on top of the valve waiting to be dropped into the cylinder. but highly unlikely at the moment. im thinking its not sparking on those cylinders as it should. pick up coil is 21 years old. and it did give me a error code. it may be possible that some dirt may have screwed the signal. i find it very odd though as its only 2 cylinders. bad pickup coil would normally equal and no start. same with icm. but it is a possiblity i suppose

 

Injectors are fired in batches not banks, 1,4,5,8 and 2,3,6,7. Did you test the injectors that you replaced to see if they were stuck open? It's easy enough to do with some compressed air. Were the replacements new, used, or reman and were they the same type and value? The newer 4 hole injectors are much more prone to sticking open than the pintle version so you could still have the same problem if that is what you used. I'd also suggest you back down the fuel pressure to stock until you sort this out and then only turn it up if you can verify it's going lean with a wideband O2 sensor.

 

Ok -- SD / batch fire (I call it paired bank because batches are for cookies, not automobiles) is really squirrely to begin with (prefer MAF conversion) and limits what you can do later......still sounds elec, but I've seen mech issues (after new builds) give similar, if not identical issues.........

 

replaced 2 injectors with holley 19lb fuel injectors. same impedance as stock ones i replaced. Plan on swapping them all to holley didnt have the money at the moment already put 7 grand into this motor. so yea.. at any rate. i believe it has to be electrical. i built it performance and built it overkill. its got high dollar mains. afr heads eddy intake. all the gaskets i used were recommended by the manufacturers of those parts. It was built with quality and longevity in mind. anyways. i would think the pick up coil would cause a no start. i need to spark test and look into ignition further if i do not recieve spark on those cylinders. and motor only has 600 miles on it. it would take a lot more to burn a valve. ill spark test it when i get time and bring home my snap on vantage pro to test pickup and icm. and spout. btw with spout unplugged and adjusting timing it does not change. now when i did clear flood mode it ran good for a second or 2 . then flooded itself out when it went back to idle. it may very well be dist cap or pickup. maybe even coil. but coil and dist cap are not that old they are only 2 yrs old or so. and if it is the pickup ill just put a msd distributor in and be done with it. I need my truck. i put alot of money in it and i really would like to enjoy it.

 

Just thought of something. cylinder 1 and 3 are next to each other in firing order. and clip on back of distributor cap where 1 and 3 are, is loose. but i cannot see any spark trails at all. and i knew the cap was loose prior to putting 600 miles on the truck. and i have 1 and 3 wires tied together. im at a loss.

 

Separate the plug wires, cross-fire is a very common problem on these trucks. The TFI e-core ignition coil delivers a very hot spark.

 

Ignition problems will not cause cylinders to flood, even if those plugs never fire the cylinders won't get enough fuel in them to do what you are seeing, you have an injector problem or a wiring short in the injector circuit.. maybe a pinched wire somewhere.

 

2X on pinched wire. I'd disconnect the two injectors wire plugs and see if they still flood. If not, then its electrical problem for sure.


How bad is it flooding? Better check your oil for gas in it, don't want to thin out the oil and kill a fresh engine.

 

its flooding good enough... its getting gas in the exhaust. exhaust tip is wet. and yea i know soon as i fix problem oil is getting changed. and i have not driven the truck only time it is started up is to do testing. its very odd how this problem showed up. was driving home from work. then i notice at stop lights and stuff it would vibrate bad. put it under a load and it wasnt noticeable. then next day drive it to work. and holy crap under powered and would buck and stutter. drove it back home parked it and there it has set for 3 weeks. havent had the time to work on it. i work 12 to 14 hours a day as a diesel mechanic. i did test injector wire with noid light and it is flashing so i dont think its staying open. im bout done with it. bout to send it off and pay someone else. getting really annoyed with it. if i had more time maybe id have better luck. but im at a loss. i dont wanna throw parts at it and play the guessing game. im a firm believer in finding then fixing with correct part.