Dirty Fuel Injectors???

My 93 GT would not start. The engine cranked, but that's it. The first two questions that came to mind were (1) Is there a spark, and (2) Is there fuel. To answer the first question, I shot some starting fluid in the throttle body and the car turned over, sputtered and died. So I figured, yes there is a spark, but no there is no fuel... Well a fuel pressure gauge tells me there is 40 PSI at the Schrader valve, so I now figure the injectors are fouled.

Does this make sense or am I missing something obvious?

$62.50 x 8 is a big chunk of change! Can I simply pull the injectors and clean them on my bench?

If I understand the Mustang Unlimited kit properly, it requires the car to be running to be effective and it doesn't run, so am I headed in the right direction by removing and cleaning the fuel injectors myself?

I would certainly appreciate any suggestions or directions.

Thanks!

Joe

Reply to
Joe Colella
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I wouldn't jump to the conclusion that the injectors are clogged. They would ALL have to be clogged severely to not allow the engine to run and this is highly unlikely. Maybe you got some bad gas or there is water in the tank. You might try some dewatering additive first or drain the tank and lines before taking the injectors out. You might want to check out the fuel filter too. You might have pressure but not enough flow. Others here might have some more suggestions.

Reply to
Michael Johnson

one can check for bad gas by getting some of the fuel pumped up and putting it into a clear jar and seeing if there are beads of water on the bottom. (very dangeroious to do this, )

When is last time you changed fuel filter? Is gas tank near empty? (if so, more crud on bottom)

pull some of the easy plugs and read them

when is last time you cleaned/replaced air bypass ?

you have to pull top manifold off to get to injectors, the rod could still be in place in the back by firewall, you have to cut that, it holds top and bottom together

Reply to
biggus

Changing the fuel filter is easy and cheap... and probably should have been done some time ago.

Really... I could have pressure, but not enough flow? I would not have expected that, but all the same, I will definitely change the fuel filter.

Drain the tank and the lines... I could do that!

Thanks!

Joe

Reply to
Steve

Checking for bad gas... Siphon some gas from the bottom of the tank, right?

Fuel filter could be 5 years old.

Tank is currently 3/4 full, but just before the most recent fill, I did run the tank damn-near bone-dry.

Pull some of the easy plugs and read them... I actually changed the plugs right after pushing the stang into the garage.

Last time I cleaned/replaced the air bypass... Could be 6 years. (Am I bad?)

I am getting the very distinct picture that cleaning the fuel injectors is not a walk in the park!

Is there anything else I should look at before ripping the manifold off?

Thanks, again!!!

Joe

Reply to
Steve

Definitely put some dewatering additive in the tank after draining it. That will clean up any residual water that may be left behind. If you still think it is the fuel injectors then I suggest pulling a couple of the ones that are easy to get to first. If they are in decent shape I wouldn't waste your time pulling them all. One other thing that affects fuel flow is the MAF sensor. I doubt it is bad but it could cause fuel delivery problems if it is defective.

Reply to
Michael Johnson

One last thing, the fuel pump might be bad. While it might be delivering adequate pressure it might not deliver the flow required.

Reply to
Michael Johnson

Injector Condition... After I pull 2 or 3 injectors, how can I tell if they are in good shape? (Gosh, I feel stupid!)

Crud in Tank... Could running the tank empty until the car literally runs out of gas be the root of all my problems?

Should I also flush the fuel line? With gasoline or some other liquid or pressurized air? How about the fuel lines between the fuel line and the injectors?

I can test the MAF sensor, how can I test the fuel pump for proper flow if the pressure reading in not conclusive?

Thanks!

Joe

Reply to
Joe Colella

change one thing at a time, fuel filter first. add dryer.

then check for bad gas. I got a load at one gas station, lots of water in it. got a hose and ran it into the fuel rail and to a clean jar, cranked the engine a few times, and got jar 1/2 full, lots of water in it, beads at bottom. Gas station had a fuel truck filling up the tanks and stirring up the water at the bottom of the gas station tanks, was a dimond shamrock, now veralio, never got gas from them again.

Reply to
bob

You can see build up on the nozzle tips but they probably need to be tested for having a proper spray pattern.

Running the tank low shouldn't be a problem normally unless there is a lot of debris in the tank. This would clog your fuel filter.

You car uses a return fuel system so a cranking the engine should flush out the fuel lines fairly quickly.

This isn't an easy task for the DIYer. Try and find a friend with the same car (i.e. 1989-1993 5.0L Mustang) and swap in their MAF and see if it starts. I assume you are using a stock MAF. If so you need to use a stock MAF or one calibrated for you injector size.

Reply to
Michael Johnson

What do you mean by "sputtered"? If you spray a good amount of carb cleaner into the open thottle body, it should run at a high idle for about 2 seconds. Not just "sputter". There is no way ALL the injectors went bad at once unless you ran battery acid through them. I think you better make sure it has good spark by looking at the spark or re-testing your "spray method". Strating fluid will help it try to start if the spark is weak. You can test the MAF by unplugging it. This will put it into "limp in" mode so the ECM wont even look at the MAF. 40 PSI doesn't sound like enough for MPFIed mustang, I would *guess* 60 but I don't know for sure(been way too long). If it is supposed to be 60 it wont run on 40. Look it up. (buy a book) BTW, fuel filters are very cheap *hint, hint*

Reply to
ScottM

FIRST THING, make sure the injectors are being triggered. Put a set of "NOID" lights in place of the injectors on the wiring harnes and make sure they flash. If the injectors are not being signalled to fire, it will never start.

Reply to
clare at snyder.on.ca

Impossible. If it is producing specified pressure it is pumping enough to start the engine. Mabee not enough to drive it down the road - but definitely enough to make it start (or at least cough pretty good) Given his fuel pressure, it's not the fuel filter either (although it may still be a good idea to change it when you find out why it's not starting now)

Reply to
clare at snyder.on.ca

OK... you have pressure at the fuel rail..... are the injectors being pulsed? With the key on, the injectors are supplied with 12 volts to one terminal.... the PCM grounds the other terminal to "fire" the injector.

Reply to
Jim Warman

It could be the pump. There is a pick up tube with a sock over it. This could get plugged if there is junk in the tank. Unlikely but possible.

Reply to
Michael Johnson

If it was plugged totally he would not have full rail pressure. If he has full rail pressure there is enough fuel to start the engine. Mabee not enough to run it, but enough to start it. I stick by my "impossible"

Reply to
clare at snyder.on.ca

I don't think it is the pump either. Usually when pumps go bad they just stop working all together.

Reply to
Michael Johnson

Very surprised someone hasn't suggested checking the ignition module. Every time mine went bad, the car would crank, almost catch, then die. If I held the key to start, and stepped on the gas, the engine would rev. You will get spark when cranking. And that's it, no mo'

Did this occur suddenly? was it running one day then not the next? I'd rule out the ignition module first. They do go bad, and are known to be in a bad spot, taking lots of heat. I'm on my 3rd or 4th in my '86 5.0. Everytime it cranks but won't start, that's the first thing I check, especially if it's a sudden onset. Doesn't matter if it ran 5 minutes ago. They die when they feel like it.

My rule is not to replace what you *think* it is, but rule out everything else until you only have one thing left and *know* what it is.... I have not seen anyone rule out the ignition module yet. I keep a spare one handy, because I know I'll need it eventually.

I'll put up a 6-pack of my home brew that's the problem.

mkl

Reply to
Mike Lenker

where is it on the 5.0 ? is it a small square bolt-on box below the distributor ?

Reply to
biggus

I think you already ruled that out by using the starting fluid to get fire. The injectors seem more likely and they all have signal and ground common to them all. I say check ground first. It's free and quick. Then go for the signal.

Reply to
GILL

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