Albizo66

Alright guys, I used to be around a lot, but then life got in the way lol. Let's see what you got..

93 4 cyl notch conversion; put everything from my 89 in there. 89 comp, 93 wiring harness.

Here's the starting issue, plain and simple : sometimes it does, sometimes it doesn't lol. Pump primes up, obviously getting fuel and spark cause it does start sometimes, plenty of voltage. When it does start, usually rolls into it, but then runs full power and strong as hell, "perfect" if you will.

When it doesn't start for me, turn the key on, hear the pump, and it will just crank and crank and crank (you hear the starter going, but won't turn over). Took it to my trusted mechanic (also does everything on the side for me). Of course, it started for him every time (not a mustang guy per se, but knows what he's doing), so he doesn't really know what to tell me..

This thing is my DD (currently drive my mom's car to and from work), so I need it to reliably start every time, cold or not. I'm thinking possibly ignition switch?

Not sure where to go here guys, appreciate all input..

Edit: this is a new problem, once the swap was done it started and ran perfect. This started in November-ish' I blamed it on being an old Ford and not liking the cold weather. Guess I was wrong

TrimDrip

That is tough to diagnose if it doesn't just quit.

I would try to figure out if it doesn't have spark or enough fuel pressure so you can narrow it down some.

mattdel

Your description "rolling into it" leads me into the direction of fuel pressure problems.

Albizo66

Also, once warm and having been drive and running for a bit, it will start on the first try. Sometimes strong, most times still roll into it.

Wouldn't a fuel pressure problem effect it while driving though? It's at full strength once going.

I do have a fuel pressure gauge under the hood, I'll check it and see what kind of psi I'm getting.

Thanks for the suggestions, please guys, keep the coming

mattdel

My fuel pressure theory is based on my experience with small engine repair. I've heard and fixed the issue "rolling into it", I know exactly what you speak of. The issue can be a series of injectors that are mildly stuck open causing a minor flooding scenario, or a leaking fuel pump sump hose causing a struggle to create pressure, or something along those lines. I bet what you're experiencing is very similar to a carb engine that is over-jetted. Theres plenty of other reasons for this to happen, but "rolling into it" is a very telltale symptom. Weak spark, weak fuel pressure, weak cylinder compression. Those are my 3 targets for that description.

Albizo66

So I go to pick it up from the shop today and I go to start it (was after the mechanic had left), took me approximately 10 times to finally get it to turn over, and it "rolled" into it again. Strong odor of fuel throughout.

I have the fuel pressure gauge under hood; with the car off, I'm at 40 psi, but when I try to start it and it's cranking, my dad said it dropped down to 0...is this normal??

EDIT: Still took it home, and once idling, and then obviously being driven, it ran perfect. Although, almost felt like something was "missing" at high RPM, could be that my more than 220 pound dad was in the car with me (i'm 175-185). I got WOP a few times, and like 85-90% a few others. Still ran strong, no misses or anything of the sort.

I'm at a loss now guys

mjr46

fuel pressure should not drop to 0 while cranking, a ground should be supplied to the fp relay when in the crank mode and the ecm knows to apply the ground to the relay when the stator in the dizzy picks up an rpm signal via the reluctor wheel passing across the hall effect switch per say/ stator, so if you have a intermitent prob with not getting a ground to the fp relay, I'd look into that, you could verify that by making sure the ecm is applying the ground to the fp relay when prob occurs, if it is and you hear a click with the relay but no FP while cranking, could have bad contacts on the FP relay

Albizo66

hey mjr, was hoping you'd reply to this; always trusted and valued your opinion..one request though. can you put that in layman's terms?

basically, find the fuel pump relay and make sure it has a ground? sorry for my ignorance..

TrimDrip

That was a good answer and a good start.lol

He basically said, look for the fuel pump relay near the maf meter on the fenderwell. Make sure when the pressure is at zero that the relay is engaging while turning over. It will click and you can feel it with your hand when it does. If it is clicking, pull it out and look for corrosion or bad signs of contact.

I have seen a bad ground near the computer cause a similar problem.

Even though it runs good once started, I would stay out of it until you get it fixed. No need in leaning it out and causing damage to the engine.

mjr46

if it's a 93 harness than fuel pump relay is where T-drip says, locate it and the wire to it that the comp uses to ground the relay coil windings, simple test light hooked to B+ and other end of light probing the FP lead from comp to relay will tell if comp is grounding relay if light lights up, but test must be done when prob occurs to verify, or simply put your hand on the relay and have someone crank car over and feel if a click is present, if it is, you know comp is grounding the relay, but still could be bad contacts in the relay.