1990 Mustang 5.0 takes forever to start

1983 Views 15 Replies 5 Participants Last post by MustangBradley, Aug 4, 2011

thepunisher88

Discussion Starter · Aug 2, 2011

I got my 90 mustang GT in on a good trade. It has a BAD problem with starting. Almost like its got a VERY bad carb on it. BUT its all factory and fuel injected. Only thing thats been removed is the Smog Pump and EGR. problem is it literally takes almost 40 seconds of holding down the starter for it to FINALLY run, and when it does finally run it kinda backfires in the intake and and have to keep giving it gas to keep it running. But after it gets a little warm it idles and runs perfect. drive it 200 miles and runs great. stop at store to put gas in it and got to hold down starter for another 30 seconds before it finally cranks back up.

When i got it it had no O2 sensor harness on it. thought that was what was wrong with it. finally found one and bought it and hooked them up and still took forever to crank, but problems got even worse, after running for about 5 minutes it starts missing BAD from idle to about 2500 RPM then runs Like a new car. So i unplugged them for now. But i got to get those fixed also.
The car has a new Temp sensor on it, New IAC valve on it, Just tested the tps and it checked out perfect. Its got good fuel pressure to the Shredder valve. Spark plugs and wires and rotor button and cap all look good. Any one have any idea what could be going wrong? I would REALLY appreciate it if anyone could give me somewhere to look. I dont want to have to take it to a shop, but its not looking too good as of rite now.

PLS HELP!!!:?:

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MustangBradley

· #3 · Aug 2, 2011

Sounds like you need to set the base timing. My distributor hold down bolt loosened and allowed the distributor to turn on its own. After that happened, it would not start.

Do a quick visual check of the factory chisel mark on the distributor base. It should be pretty close if not right at the notch in the block.

As Ninja mentioned, you could have weak spark too. Before you start replacing parts though, make sure you have the current parts set up right.

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MustangBradley

· #5 · Aug 2, 2011

Don't buy a coil if you don't need it!! Waste of money.

Did you pull the spout connector when you tested base timing?

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MustangBradley

· #7 · Aug 2, 2011

When you were clocking the distributor, the computer was trying to "undo" what you were doing. If you have never removed the distributor, don't do it now. There is no need.

Do a search on setting the base timing. There is a "Spout Connector" that you must remove to tell the computer you are setting the timing, so it won't make any adjustments on its own.

If I was in your situation, I'd set the timing to stock so you can see if you can get back to a good running condition. You don't need a timing light to do this.

If you look closely at the base of the distributor, right where it goes into the block, you'll see a chisel cut, or mark. This was made at the factory once they got the initial timing set. If you look at the block, right where the distributor goes into it, you'll see a ridge that has a step down (if you go left to right). The mark on the distributor should be right at that step down.

Locate the spout connector (I forgot where it is on your car) and remove it. Loosen the distributor hold-down bolt and rotate the distributor until the mark lines up with the step down. Tighten the hold down bolt.

Now, with the spout removed, start the car. Let it idle for a minute then put the spout back in. Your timing is now reset to factory.

Without seeing the mark, I can't say. Take a pic and post it.

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MustangBradley

· #13 · Aug 3, 2011

Of course, it is best to use a timing light, but with the info from your previous posts, I am merely trying to get you back to a known good baseline. You don't need a timing light to set the timing back to stock, since that is what the mark is for that I described above. Once you get the timing to stock, you'll be able to do more diagnosis.

You'll want to pull codes, then kill the memory and start it up again. Let it relearn for about 10 minutes of idling and then pull codes again. Compare the two lists. I expect the O2 sensors to be on the first list, but if you have them working properly, they should not be on the second list.

Once you get to this point, you should have an idea of what you need to investigate further.

Have you ever had the distributor out? Has the car ever run right for you? If I read your first post correctly, it has never run right. I wonder if you are one tooth off on the distributor. I was one tooth off, and had a similar set of symptoms to what you have. If you suspect the distributor has been out, it might be worth your time to find TDC and make sure the rotor is pointing at the Number 1 plug wire.

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MustangBradley

· #16 · Aug 4, 2011

To kill the memory, remove the ground cable from the battery, and turn on the head lights. This will drain the computer of any residual current, and kill the KAM.

Don't forget about the Spout connector. This is important to remove whenever you mess with the timing, since the computer will fight you if it remains in place.

When you try to switch teeth, try counter-clockwise first. When you have the distributor back in, make sure your mark is where the step-down is, so it will be at the factory position.

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