I am having trouble with my 94 Dakota 3.9 Magnum being slow to start after sitting several hours.
This complaint has been made many times but none of the answers I've read seem to make any sense for my problem, because the answers mostly apply to a NO START situation. Mine will start, it just takes about three times as long as usual.
Also, most of the answers involve components that will not malfunction just on the first start after a long sit. At least as far as I can see. I'm referring to such components as O2 sensor, TPS, Crank sensor. If any of these things were bad they wouldn't suddenly get well after the first start of the day.
I can't afford to take it to a dealer who has (or had) $50,000 of test equipment.
Please remember I do not have a NO START situation.

 

By "slow" you mean "engine turns over slower than normal" or "it turns over at the normal speed, it just has to crank for several seconds"?

If the former, there's several possible causes - oil too thick, battery low are proximate causes, but the reasons for either can be a bit more detailed.

If the latter - fuel pressure is bleeding down, and you have to crank it until the pressure builds up enough to actually do any good. That's caused by a leak; can be a bad injector dribbling, the fuel pressure regulator leaking, or the fuel pump leaking back into the tank. Good news, the latter two can be replaced with the fuel pump assembly on your 1994; bad news, you have to replace the fuel pump assembly on your 1994 to fix the regulator and/or pump. *grins*

(My wife's 1991 Cougar is starting the "takes longer to crank"; I don't know why a 27 year old fuel pump would be leaking on it internally ... *grins* )

RwP

 

Can you spray some starter fluid down the carb throat?

That may answer the fuel bleed down??

 

Well, a 1994 has no carb, so that's kind of difficult. Unless the motor's been swapped to carburated, in which case, possibly; and most of what I'm typing won't matter.

What you can do, if that's it, is a three step process:

1) Turn the ignition to ON (not START!), wait 10 seconds, turn it off.

2) Repeat 1.

3) Repeat 1.

4) Now, turn it to START.

The 3 "Turn it on, wait 10 seconds, turn it off" in a quick sequence will reprime the fuel line.

A quick CHECK is to put a fuel pressure gauge on the fuel rail (that's what the Schrader valve is for!), see what the pressure is; turn it on and off (leaving it on for 10 seconds, then off, then repeat) until it builds to the proper pressure (memory says about 40PSI; check the factory service manual to verify the proper pressure), then turn the ignition off and see how long it takes to bleed down.

That gives you hard numbers as to how quick it drops, and how many of the "Turn it to on, wait 10 seconds, turn it back off" it takes to get it back to proper pressure for your fuel injected motor.

I'd bet the regulator or pump due to age; it may, however, be an injector dribbling down. Check the dipstick after an overnight; is there any gas smell to the oil? If not, it's probably not an injector (you may want to plan on getting them properly cleaned; this can be done at home, see YouTube for several videos. You can also plan on doing a full swap for like-new or better-than-new performance; that's what I did on the 1991 when I had two injectors fail on it (they just needed a complete cleaning, but since I found a matched set for $125 at the time, I just swapped all eight single-nozzle injectors for eight 4-hole injectors. Restored the pep and vitality the Cougar had!)

If you do the pump and regulator, be very VERY careful of the anti-roll over valve; it's not included, you have to move it over, and it's kind of breakable (as has been found by others on this forum!) There's a Dorman replacement available; I'm not sold on Dorman unless There Just Is Not Another Choice.

RwP

 

Thanks for your replies Ralph.
I definitely meant slow starting, not slow cranking. I realize many people seem to think cranking and starting are synonymous.
I replaced the fuel pump assembly about two years ago and I realize that doesn't mean it can't be bad now. I'm leaning toward the bad injector idea. I think I will just order a set of Bosch recons and see what that does. I haven't had the power for a good while that it used to have anyway, possibly another sign of bad injectors.

 

Take off the air cleaner and spray the fluid directly in the throttle body...like you have done if it were a carb.