94 ranger 4.0l/standard

[alwaysFlOoReD]

I just put the [running when pulled] 4.0l out of my racetruck into this 94. The ecu is the original 94 that I was using in the racetruck. I have everything installed but the cooling system. A brand new battery. New fuel in the tank that had some old fuel from years ago....possible problem. Fuel pressure builds up to 38psi after 3 or 4 key turns. Wires are hooked up. Sparkplug wires are in correct order. The old motor had oil fouling on 3 of the sparkplugs. The new [race] motor has good compression on all cylinders. I don't have the cooling system radiator installed.

So.... The motor cranks over and seems to want to start. It fires frequently but won't catch except 2 times. Both those times it revved to ~ 3000 rpm and I shut it down almost immediately.

Can the no cooling system cause a problem? I have run engines before without cooling for up to a minute but they were not computer controlled.

Wondering about the o2 sensors being fubar because of the old motors oil usage? Wouldn't the computer go to limp home mode in that case? The race truck had one o2 sensor, this 94 has two. In the racetruck the motor idled fine.

I'm working where there is spotty phone reception but I can usually get to this site but it's a pain to look up info.

Any help appreciated,
Thanks,
Richard

 

[RonD]

Engine will run without cooling system.

And O2s can't cause a no run/no start, rich or lean running yes, computer doesn't use O2s until they warm up to 600deg in anycase

'94 4.0l uses an EDIS module for spark, it is connected directly to the Crank Position(CKP) sensor, and coil pack.
EDIS then sends the CKP timing pulse to the computer so it can time fuel injectors.
EDIS will start spark without computer connection, it is autonomous in that respect, but it does need computer feedback to get "vacuum advance" data

It is hard to tell if fuel pump is coming back on when engine starts, can you leave the fuel pressure gauge hooked up and see if pressure is staying above 25psi after it fires?

You can "hot wire" fuel pump so it stays on anytime key is on by grounding the Fuel Pump slot on the VIP/OBD1 connector in engine bay
Seen in this drawing: http://www.therangerstation.com/tech_library/OBD_I.shtml
That slots wire is is spliced to the Ground for the Fuel Pump relay, so when grounded with key on it is the same as computer grounding the relay, so pump stays running even with engine off, doesn't hurt anything.

Cold engine needs extra fuel to run, large vacuum leak can cause too lean a mix to stay running, but it would have to be a pretty big vacuum leak, lol.
REVing to 3,000 could be big vacuum leak
Or IAC Valve is stuck Full open

 

[alwaysFlOoReD]

I checked all the vacuum lines and all were good. I decided to check the throttle and it was stuck open a little by the wiring harness;

I then opened the throttle to full for the clear flooded engine. Still not catching.


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[alwaysFlOoReD]

Fuel pressure is at 28psi when jumpered and falls to 22-25 when cranking. It stayed at 28 when doing the clear flooded engine.

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[alwaysFlOoReD]

Let it sit for a bit and it fired up and idled OK. Vacuum gauge is near 0 though so will check that after I button up the radiator. Thanks for the help.....so far

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[alwaysFlOoReD]

Misread the vacuum, its sitting steady at 18psi, which I believe is good at my altitude.

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[RonD]

When you said vacuum was at 0, and it started, I though you had installed a diesel engine by mistake

18 is good, steady is even better

Good work on finding the stuck open throttle plate

 

[alwaysFlOoReD]

Well, its running...and not too bad. Idle is at 1200 according to the tach, which I think is high for a standard. Found one fluid leak where I forgot to righten a heater hose down behind the alternator bracket. Luckily I was able to twist it and reach with a screwdriver. All lights except reverse works, and it looks like the trailer wiring is a mess. Vacuumed all the mouse shit, glad I had the glove box opened facing down as I've seen them half full of shit and piss....no fun to clean. Electric 4*4 isn't working. It has cruise but haven't tested it yet. It should be a good winter beater once I've done fixing. Needs a stereo and speakers too.

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[chewy012]

Just nit picking, your vacuum gauge should read 18 inHg, not PSIG. Maximum vacuum possible is -14.7 PSIG or 0 PSIA.

Inches-mercury (inHg) to PSIG is about 10 inHg to 4.9 PSIG. So you're really only pulling about 8.5 PSIG of vacuum. But, I'd agree your 18 inHg (in-hoogs) is normal, that's where mine reads, I'm at 6000 ft elevation.

Anyway, just FYI...

The more you know.

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[alwaysFlOoReD]

Thanks. I knew that 35 years ago in high school shop class...oops.

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