XR4ti won't start! Any suggestions?

[Merkurstein]

Just to start off. Want to say hi to all the fellow members. It's been years since I've been on here so I had to start a new profile. Here is the current issue/problem.

Drove my XR to the local grocery store last week, car drove fine on the way there, came out of the store tried to start it and it just cranked. Had it towed home. Since then doing some troubleshooting when you turn the key on you here the fuel pump priming but it doesn't shut off. No click and just keeps buzzing. Car is getting 40psi to the fuel rail but builds up kinda slow and doesn't put out 6-7 ounces of gas in 10 seconds as I believe the shop manual CD stated it should. Also, the car is not getting any fire from the coil but is getting power to the coil plug. I have checked a few fuses and relays and haven't found anything so far. I originally thought when it happened the pump just went out on me but no spark changed my thoughts on the issue. I did put gas in the tank prior to leaving (about 3/4 full tank) and I know the tank is pretty messy on the inside but it having no fire from the coil makes me think it something else (bad ground, inline fuse blown, ECM, distributor module) Any thoughts or suggestions??

Few of the car's specs: 87 XR4ti repinned LA3 cardone unit & big VAM, TC TMIC, 3" DP& exhaust, E3 manifold stock T3 on 15psi, RR cam, WC T5

[uroford]

TFI? I didn't have trouble for years and then mine quit. I found on replacement that the grease was so old that it was kind of chalky, I wasn't careful cleaning the engine bay about half of it had washed off.

[zxr250cc]

Hi all,

Mine did this when I was working on it last year. I changed the various small distributor ignition related parts and then found that it was actually the coil.... Try the coil first. Just a thought.

Cheers

[Merkurstein]

Thanks for the suggestions, I'm gonna check/change out some of those. I have a lot of extra used parts from several parts cars over the years. I have a milk crate with about 5-6 distributors, two ECMs (PF2 & PF3) plus an extra good fuel tank I was gonna replace it with from a 40k xr that was wrecked. Putting it up on jack stands today and start the process of elimination. I'll keep posting updates.

[Merkurstein]

Update: Changed coil and cap still no fire. Probably change the module next. Gonna pull the inline filter and see how nasty it is, I know it needs to be changed anyway. Just can't figure out why the intank pump keeps running and doesn't prime and stop? Like it's not building enough pressure(weak or the screen got clogged) but would that stop it from firing? Maybe the old ECM from my 88TC went out, I can change it out for a PF just to see. The fuel pump in the tank not priming and clicking off makes me think something is up there.

[sabre]

The bit where you found that the fuel pump stays on any time the key is in the ON position got my attention. In my experience, that, accompanied by the no-start, is a rare symptom, and is usually caused by a bad PCM. Normally, when the key is turned to the RUN or Crank positions, the PCM turns on the fuel pump (by grounding the fuel pump relay) for a second or two then shuts off. The PCM will only keep the FP relay grounded when it is receiving an rpm signal from the PIP sensor (like when the starter is spinning the engine, or the engine is running). See if the pump still runs continuously if you disconnect the TFI module connector. This will eliminate the possibility of some erroneous signal from the PIP/TFI assembly triggering the PCM to ground the fuel pump relay. Also, a bad ground to the PCM may also cause this type of problem.

[zxr250cc]

If it is the PCM I have an old one from an '85 auto model I am not using. I have had it since the late '80's as a spare and never needed it.

Cheers

[Merkurstein]

Thanks for all the suggestions. Before I read sabre's reply I changed TFI module and still nothing. I came in the house to cool off and checked the forum and unplugged it as sabre said. The pump kept running, I tried changing the PCM ,unhooked the battery and got one of my two spare PCMs(the PF2) unplugged the LA3 plugged up the PF2 hooked the battery back up turned the key to ON fuel pump came on and clicked. Then turned the key over and it started! She is running a little rough but I will have to retime it cause I had to turn the distributor a lil to switch modules. I have been thinking of going back to a stock PCM and small VAM anyway. I have more stock parts (PCMs,VAMs,Engines,etc) from parts cars over the years. I'm just using it as a driver now and the stock setup on the engine is good enough for what I want. I'm gonna do some more work to it while I have it on the carport and on stands maybe changethe O2 sensor, run new vacuum lines and other stuff. Thanks to everyone for the help and to zxr250cc for offering the PCM.