1987 ford E350 460 7.5L backfires

[gulfstreamer97]

acquired a 87' E350 econoline w/ 460 7.5L EFI cab over motorhome. this thing sat for some time owner told me "the fuel pump needed to be replaced, parts are there" replaced parts given (fuel pump, filter & lines) ran to an external fuel supply. didn't want to clog new filter. purged air from line engine cranks over (sounds good) wants to start but doesn't. spray a little starting fluid in breather and starts to turn over. runs for about 3 r 4 seconds, dies. repeat procedure and same. repeat again and it back fires from throttle body hose. any help would be much appreciated. this motor home is not my main traveler. this is one that was handed to me as a project. but would like to get running for small trips with family. that way i dont have to take out "UNC" short for uncle, my 1997 palm breeze, gulf stream. thanks in advance. also first time to forum so if there is anything i need to put in posts to make this as easy as possible please mention

[ron_dittmer]

My dad bought a 1987 Econoline E150 new in 87 which had a fuel injected straight 6-cylinder 4.9L engine. I would assume fuel injection was used in every 1987 Econoline.

Because the vehicle sat for so long, it could be that you have rodent damage. They love to chew on the rubber and plastic insulation. Bare wires might be exposed touching ground or each other, or even corroded to the point of breaking, after being exposed so long. I advise to inspect all wiring including spark plug wiring and 12V wires under the hood. Also inspect all vacuum lines for the same rodent damage. Chew marks will be the indicator as to how it happened.

[4x4van]

Just a nit-pik, but most '87 E350s with the 460cid are carb, not EFI. While the trucks got EFI in '87, most E350's didn't get it till '88. Sounds like the OP might have an '88 chassis, not '87.

[DRTDEVL]

CharlesinGA wrote:
This is a 460, EECIV engine, and if I recall it has throttle body fuel injection. Very little ever goes wrong with these injection units.

Unless you count vacuum leaks, they are notorious. Usually that would result in a very high idle while the computer attempts to compensate, but this can also result in a no-start due to being too lean.

[CharlesinGA]

theoldwizard1 wrote:
First, with a fully charged battery, turn the key to ON. Your should hear the fuel pump (typically in the tank; listening at an open gas cap helps) for about 10 seconds. If not, you have a problem with the fuel pump or wiring including the inertia switch.

Second, the the key OFF and check if there is pressure in the fuel rail at the engine. There should be a Schrader valve (looks like a tire valve) on the fuel rail. Remove the cap and depress the inner button and you should get a good squirt of fuel. If not, you have a blockage in the fuel line, a problem with the pressure regulator, or the check valve is allowing fuel to leak back to the tank.

Third, after the engine has not been cranked for a couple of hours, start cranking it for about 20-30 seconds. If it does not start, stop cranking, press the accelerator pedal all the way down to the floor and start cranking again. After about 10 seconds and then start to slowly release the accelerator pedal. If the engine starts, you have a stuck idle speed control (IAC) valve. Sometimes these can be cleaned, but sometime they have to be replaced.

This is a 460, EECIV engine, and if I recall it has throttle body fuel injection. Very little ever goes wrong with these injection units.

Sounds like crossed wires, and no or little fuel.

Charles

[DiskDoctr]

Shortlist for that engine, been there done that.

1. New sparkplugs

2. New plug wires, distributor cap, rotor- went with MSD, low resistance wires

3. New ignition module (yeah, it burns off, pull the distributor wire off it and check- went with MSD

4. Test/replace fuel pump relay, it likes to eat them up

5. Delete Catalytic converter (to "test" -up to you what you replace it with or leave it off). As soon as you have firing issues, raw fuel dumps into the cat and clogs it. (You could disconnect exhaust pipe from the manifold on driver's side so there is about 1/4"=1/2" gap and see if it starts and stays running. If so, cat is clogged)



I've done all the testing and isolation, chased it round and round. Everything I found was fixed and now runs like new!

[theoldwizard1]

gulfstreamer97 wrote:
spray a little starting fluid in breather and starts to turn over.

First, lets get our terminology straight. "Turn over" means crank. no start. It sounds like the engine is always "turning over" and only occasionally actually tries to start.

donn0128 wrote:
All gas motors need three things. Air, fuel and, spark.

... in proper quantities and AT THE RIGHT TIME !

First, with a fully charged battery, turn the key to ON. Your should hear the fuel pump (typically in the tank; listening at an open gas cap helps) for about 10 seconds. If not, you have a problem with the fuel pump or wiring including the inertia switch.

Second, the the key OFF and check if there is pressure in the fuel rail at the engine. There should be a Schrader valve (looks like a tire valve) on the fuel rail. Remove the cap and depress the inner button and you should get a good squirt of fuel. If not, you have a blockage in the fuel line, a problem with the pressure regulator, or the check valve is allowing fuel to leak back to the tank.

Third, after the engine has not been cranked for a couple of hours, start cranking it for about 20-30 seconds. If it does not start, stop cranking, press the accelerator pedal all the way down to the floor and start cranking again. After about 10 seconds and then start to slowly release the accelerator pedal. If the engine starts, you have a stuck idle speed control (IAC) valve. Sometimes these can be cleaned, but sometime they have to be replaced.

[77rollalong]

Check fuel pressure on the fuel rail test port, also could have problem with the mass air flow sensor between the throttle plate and the air box, and scan it to see if you have any codes stored could help as well, if you need the fuel pressure specs i can look them up.. one other thing to check is the fuel pressure regulator , could try and pinch off the return line to see if that helps too

[garyemunson]

Engines that sit for a long time suffer from the fuel going bad. There will be so much gunk in the tank, removing it and having a radiator shop boil it out is the best course of action. Backfiring on engines that have been stored is most often from sticking intake valves. The bad fuel leaves deposits on the valve stems causing them to be slow (or non) closing. A sticking intake valve will lean out the air/fuel mixture to the point the engine cannot start without the starting fluid. Is the backfiring random or does it seem like it is occuring on a regular basis? If it is one sticking valve, you can determine which one by pulling plug wires one at a time until the backfire stops (assuming you can get it to run long enough to tell). With fresh gas and Techron added to the tank, it often goes away. If not, worst case you'll need to pull the head(s) to fix it. You might want to pull the valve covers and watch the valves as the engine is cranked over. A sticking valve is pretty obvious. I've had luck freeing stuck valves using B-laster penetrating oil without pulling the head. I'd remove the valve cover and since the valve is probably slightly open, a fitting to allow you to apply compressor air pressure to the cylinder won't really do the job holding the valve closed, I insert clothesline into the sparkplug hole until I can't get any more in then turn the engine by hand to jam the clothesline up against the valves. Now the valve cannot fall into the cylinder when you remove the keeper, spring cap, spring, and valve stem seal. Now you can squirt penetrating oil down the valve stem. You can wrap some electrical tape on the valve stem and after rotating the engine a little to get some free play on the valve, use a pliers to rotate and move the valve up and down to help the penetrating oil do it's job. Beats pulling the head. I'd also suspect something in the EFI system is plugged up if starting fluid is the only way you can get it to run. Since it will fire on the starting fluid, the ignition system is probably OK. You need to put a gauge on the fuel rail to make sure the injectors are getting correct fuel pressure. A "noid" light that fits your Ford plugs into the fuel injector harness and will tell if the injector is getting voltage to open (flashes each time the injector is pulsed). If that is happening and the engine is not trying to start, the injectors themselves are probably plugged with stale gas deposits. Would need a new/rebuilt set to fix that. Not much way to clean them properly in the field. As you can see, letting gas go stale can cause a myriad of problems that can get expensive to fix. Old time mechanics would often dribble automatic transmission fluid down the intake to help lubricate a sticky valve (and fog the neighborhood for mosquitoes). On modern engines this will wreck sensors. Don't do it.

[azdryheat]

You've got more problems than fuel supply and that's the backfiring. The fuel is being ignited when the intake valve(s) are still open.

[IBcarguy]

If it starts for a few seconds when putting fuel to the intake, it confirms the fact that it's not getting fuel. You've got no fuel pressure or restricted fuel pressure. It's a process of elimination at this point. Clogged filter, collasped intake sock in the tank, weak fuel pump, etc. Bad fuel but not likely.

[T18skyguy]

If it sat for a longtime the fuel could have gone bad. I would drain out the old fuel and put fresh stuff in.

[Home_Skillet]

Double check plug wires, make sure they are oriented right.

[donn0128]

All gas motors need three things. Air, fuel and, spark. Your missing one of those.