EFI Prob in my ford 87 5.0

[bedsbronco75]

I recently picked up on my dads project truck, a 75 bronco which he installed a 1987 ford thunderbird v8 into. It had been sitting in the AZ desert (no cover or building) for about five years and when i got it, it seemed that anything not in direct sunlight didn't get beaten too bad, just a little dusty. Under the hood however some rats got in and chewed a bunch of wires and that is the extent of the damage i have found so far. Now for what i have done.

I cut out all sections of chewed wires i could find and spliced them together. I have replaced the igniton coil and took a jacobs system out of the circuit and have gotten spark (going to the distributor, i have yet to check the plugs). I have replaced a low pressure filter just outside the main gas tank and the high pressure pump that is just past the selector for the fuel system. So now I have fuel (i have not checked the injectors yet either). Now my fuel lines were dry when i opened them up and the fuel filters only had a little dirt in them so i dont think a clogged fuel line or filter could be a problem but i will check anyway.

Here is where i am functionally. The bronco turns over very well and has air going in the intake. What i cant figure out is why it wont start. It sounds like it fires a little when i try to start it but it doesnt quite have enough power to actually start the engine. So what i have figured out is that the computer is keeping the fuel mixture too lean. Does anyone know with the information i have provided what might be the next best step? I have found online there could be a vacuum problem but i want to make sure that i dont miss something small that i havent come across yet. Thanks to those who help.

PS feel free to ask anything else, i may have left out important info, i am new to this after all.

PSS As of 2/10/09 I got her to fire up. thanks again for your suggestions. below i wrote up what happened. but i do have one new question at the very end if you have any suggestions for it.

 

[PROJECTJUNKIE]

So it starts and dies, or just sputters, or tries to run until you turn the key from Start to Run? Check for a good hot spark at the plug, if you have that, spray some starting fluid into the throttle body, if the ign and compression are good, you can run it on ether alone. If this doesn't do it, you have compression or ign issues.

I have had fords that start while the key is in the Start position, but die when pulled back to Run. On some models the fender mounted starter relay powers the ign in Start mode, if there is a problem with the ign switch or circuit, this will pop up.

 

[bedsbronco75]

It sounds more like sputtering. The whole engine is shaking through the process like some combustion may be happening, but not enough to start it? I had tried some starter fluid before i replaced the pumps and got a similar response; a strong sputter like it was trying to start but didnt have quite enough of whatever i am missing.

 

[Stangfather]

TFI module?

before you get all crazy check spark at the plugs or do a complete tuneup and go from there, also, the gas probably went bad so id replace the pump strainer and in line filter then cycle the pump till its pushing fresh fuel out the fuel fitting on the rail.


verify spark and fuel delivery from there, and set it at stock timing by the dist mark.

 

[fordtrucks4ever]

If spark and fuel pressure are good, I would pull injectors out and soak in lacquer thinner for a couple hours then blow them out till clean.

 

[Ryan]

http://fordfuelinjection.com/?p=23

 

[PROJECTJUNKIE]

A little more backstory, did this thing ever run with the efi 5.0? Or was it a half finished project?

Check the basics before taking stuff apart and spending money, try to isolate the problem to either fuel, ignition, or compression. Its way harder to keep a cool head and diagnose somthing AFTER you've sunk 2 days and $200 into it and its STILL doesn't run

If you have fuel problems, with a can of ether you can keep it running, and run it at high rpms nice and smooth, it takes a couple of seconds to get the hang of it (how much throttle, how many squirts of juice) if you have tried that and it didn't work I'd look into ign/compression issues. Make sure its wired for the 5.0 HO, not the old firing order, make sure your timing is somewhere near spec. If this ran on bad gas, the intake valves can very easily be gummed up and stick slightly open, causing it to run awful. It can also lead to bent valves.

 

[Viperwolf1]

If spark and fuel pressure are good, I would pull injectors out and soak in lacquer thinner for a couple hours then blow them out till clean.

The used injectors I picked up with my motor had been sitting at least 4 years and were so gummed up they would not open until I soaked them for several days. You can test them in place by applying 12v and listening for a click. If they don't click, they don't open.

 

[bedsbronco75]

Thanks for the suggestions guys. yes it has run fine with the 5.0 before, even drove it down to the shop for a brand new exhaust system. Heres an update. We went over to my bronco today hooked up the battery and put some more fuel in (apparently i have a shamefully small tank, it spilled everywhere). We charged it up and after a few no goes, we give it some gas while it is turning over and it fired up. we let it run for about 20 min and it is running real smooth but strong. my theory is that the injectors might have been a little clogged like some of you have said but the cleaner i put in the tank must have knocked enough of it loose the other day, to fire up tonight. Should i still pull the injectors (and get them cleaned) before i go out in a few months or from your experience should they be ok at this point?

 

[rjlougee]

Should i still pull the injectors (and get them cleaned) before i go out in a few months or from your experience should they be ok at this point?

As long as you can verify that all of them are opening and closing AND that you're not getting a code indicating one of the banks is running consistently lean, you should be good.

Either test fails, pull them and clean them.
Joe

 

[Viperwolf1]

As long as you can verify that all of them are opening and closing AND that you're not getting a code indicating one of the banks is running consistently lean, you should be good.

Either test fails, pull them and clean them.
Joe

Even better than this would be a cylinder balance test.

http://sbftech.com/index.php?PHPSESSID=43587d2762a03612dce03e5423613882&topic=2471.0

 

[rjlougee]

Even better than this would be a cylinder balance test. [/url]

Unfortunately, you cannot run a cylinder balance test on a batch fire injection setup, it must be SFI.

OK, nevermind, for some reason I was thinking this was an '87 5.0 from a truck. You can run a cylinder balance test, although the manual does caution that it's not an accurate indicator of injector problems.

From the Probst: "NOTE: the cylinder balance test cannot find a bad injector because it looks for differences. It will not point to an injector that is not flowing any fuel. Check the appropriate plug appearance....." In other words, if the injector isn't flowing fuel, then there is no difference when that cylinders spark is cut off, it still won't contribute.
Joe

 

[Viperwolf1]

Unfortunately, you cannot run a cylinder balance test on a batch fire injection setup, it must be SFI.

OK, nevermind, for some reason I was thinking this was an '87 5.0 from a truck. You can run a cylinder balance test, although the manual does caution that it's not an accurate indicator of injector problems.

From the Probst: "NOTE: the cylinder balance test cannot find a bad injector because it looks for differences. It will not point to an injector that is not flowing any fuel. Check the appropriate plug appearance....." In other words, if the injector isn't flowing fuel, then there is no difference when that cylinders spark is cut off, it still won't contribute.
Joe

I agree that it won't point directly to a bad injector but it will indicate a cylinder that isn't contributing whether due to bad plug wire or valves or hole in the piston or non-functioning injector. When the computer kills that cylinder during the test and there is no rpm drop it shows that cylinder as bad.

 

[bedsbronco75]

Definately will do. Thanks again.