91 Park Avenue Won't Start

[GScheel]

Hello All,

I have a 91 Park Avenue that my son has been driving. A few days ago he told me that the battery warning light was on. I checked and it was not charging. I had the alternator and battery tested and both were good. After some hunting I found a fuse panel under the passenger side of the dash board that had one blown 15A fuse. I replaced the fuse and everything looked good. The engine started and the battery light was out.

However the next morning my son got about a half a mile from home and the engine died and would not restart. My dad checked the fuel pressure at the test point on top of the intake manifold and it was low. I replaced the fuel pump relay and it appears to have fixed the pressure problem but the engine still will not start. It turns over but doesn't fire.

Can anyone suggest where I should look next?

[GScheel]

A little more testing has led me to the fuel injectors. They are getting power but they are not 'pulsing'. According to my manual that is controlled by the ECM. I happen to have an extra ECM for this car but swapping it out gives the same behavior. Can anyone suggest what else might be causing this?

[Mickey#1]

Could be a bad TPS (throttle position sensor). If the ECM is seeing high voltage from the TPS then it'll go into "clear flood mode" & won't ground the fuel injectors.

Do you have spark? if not then the problem is more likely to be the crank sensor, ICM or the wiring between them.

[GScheel]

I'm not too knowledgeable about the TPS. It has three wires going to it and all voltages are roughly the same. The blue, grey, and black wires all have about 0.5V on them when the key is off and about 10.3 volts when it is on. When the engine is turning over the grey and blue wires have about 6.5-7.5 volts on them and the black wire has about 0.5-1.0V. I have looked around on this forumand it looks to me like I should have something like 5V on the grey wire at idle but I can't find any other information about what voltages to expect. Any opinions on these readings?

[GScheel]

Another update - I appear to have lost fuel pressure again. I am starting to think that I am out of my depth.

Also, spraying starting fluid into the air intake doesn't get it to fire either. I did have spark when I tested it the other day.

[maxwedge]

If it won't start with starting fluid you have no spark, recheck that.