stumped!

[samx227]

Alright so here's the story.. 1990 ford ranger 4.0l v6..start off with what I did.. M5OD swap, used ecm out of 90 mazda navajo (5 spd, 4x4, 4.0l) truck ran great after swap been drivin it for almost 2 mos now. Truck took a swim in the river up to the headlights and cab filled up w water. Pulled it out and did normal procedure (pulled spark plugs, cranked motor over and it spit out the water, cleaned intake area and replaced air filter. All was well and the truck ran great for about 3 more weeks. Decided I'd take it on a 70 mile trip out and do some camping. Ran great on the hwy. Found some clay puddles out on some trails and went through em but they were mostly just water. Truck still ran fine. Fired it up next day to go to the general store and noticed when I turned onto the hwy it missed a little..weird. kept driving, stopped at the store, came out fired up and started drivin. Hit 3rd gear and engine missed/bogged again. Weird. Kept driving and about halfway to camp it bogged out and wouldn't go anywhere. No cel, would just turn over and over and over. Thought it was the fuel pump. Jumped the relay and you can hear the feul pump turn on. Checked up front and could smell feul, pushed in the schrader valve on the fuel rail and it squirted fuel. Replaced relay. Still no fuel pump on ignition. Checked spark, just cus. And we have spark. Noticed that when truck is put into accessory the cel doesn't come on for the quick second that it usually does.. tried to pull codes..no signal and no flashy cel. Started to thinkk it was the ecm so I swapped in the auto ecu to see if it would fire up. No start and still no cel. I am stuck anyone have any idea what to check next? Thanks.

 

[RonD]

Check the EEC relay next to the fuel pump relay, it powers the injectors along with the fuel pump relay.

With spark and fuel pressure engine should start, unless injectors are not opening.

Check injectors for 12v with key on engine off, the ecu grounds the injectors to fire them, so each injector should have 12v when key is on.

Have you tried starting fluid just to make sure spark is happening at the right time?

The ecu controls most things by grounding so check the ground points around the ecu, if these get loose or dirty the grounding is intermittent, and it uses several grounds not a common ground.

 

[samx227]

Okay so it wants to start with starting fluid.. that kinda says fuel problem correct?
Going to check injectors tonight, and crank position sensor (guy at work said to check it).
All relays and fuses goood. Still no CEL on accessory or feul pump, and still won't go in KOEO mode.
All grounds and visible wires seem to be fine.

I am really curious on why I'm not getting any sign that my ecm is getting powe. Is there and easy way to check?

 

[kunar]

check compression. starting fluid will still try to fire even with extremely low compression. when it cranks, does it sound like normal or does it crank over really quick and easy?

 

[samx227]

It does seem to crank over slightly faster than usual which worries me about compression. Was thinking maybe the timing belt broke, but them remembered its a chain, which rarely fail I've heard and I woulda heard chain slap prior to having any problems I would think.
I will check compression!

 

[kunar]

It does seem to crank over slightly faster than usual which worries me about compression. Was thinking maybe the timing belt broke, but them remembered its a chain, which rarely fail I've heard and I woulda heard chain slap prior to having any problems I would think.
I will check compression!

given the circumstances, id be suspicious of the cam timing set. ive personally seen 2 failures on that style timing set, one on my 2.9 and one on my 4.0. check the timing and get back with us, im very curious now. oh, and the way they fail... the lower sprocket shears off it's half-assed key. the chain stays right where it's at, it just doesnt spin, no chain slap.

 

[samx227]

Okay so amateur hour here, lol what's an easy way to access the timing chain? If there is an easy way...

 

[RonD]

Timing chain seems a long shot on the description of the problem.

tensioner could be broken, causing a lag between crank and cam.
Pull off distributor cap, turn crank manually in both directions, watch rotor move, it should move with the crank, via the tight timing chain.
If tensioner is bad there will be a very noticeable lag as chain loosens then tightens when crank direction is reversed.

If rotor doesn't move at all then timing chain is broken, but you would notice a distinctive lope while cranking, like when doing a compression test with all spark plugs out.

Is there a CEL light in RUN position?
And Fuel pump noise for the 2 seconds?
The EEC has to be active to ground the fuel pump relay to send power to the fuel pump, so if you hear the fuel pump then EEC is getting power.

Not having CEL when key is at ACC could be a switch issue

 

[kunar]

Timing chain seems a long shot on the description of the problem.

tensioner could be broken, causing a lag between crank and cam.
Pull off distributor cap, turn crank manually in both directions, watch rotor move, it should move with the crank, via the tight timing chain.
If tensioner is bad there will be a very noticeable lag as chain loosens then tightens when crank direction is reversed.

If rotor doesn't move at all then timing chain is broken, but you would notice a distinctive lope while cranking, like when doing a compression test with all spark plugs out.

Is there a CEL light in RUN position?
And Fuel pump noise for the 2 seconds?
The EEC has to be active to ground the fuel pump relay to send power to the fuel pump, so if you hear the fuel pump then EEC is getting power.

Not having CEL when key is at ACC could be a switch issue

4.0, Ron. No distributor. I agree that the timing chain is a long shot, but in my experience the symptoms fit perfect. from the sounds of things, if he has fuel and spark, he has eec power. no CEL is a little weird, but i suspect its an unrelated issue. also, ive seen these timing sets fail in a way that leaves the cam out of time, but still moving.

best way to check at this point, IMO, is a compression test. no sense in tearing down the front of the engine to visually inspect the timing chain. if you get low compression on all cylinders, then pull the front timing cover (pull all the accessories, harmonic balancer and water pump, youll be able to see it from there)

have you tightened/loosened the harmonic balancer bolt recently? put a wrench on it for anything at all?

 

[samx227]

I am not getting fuel, only way I can get feul is jumping the fuel relay plug. You can here the feul pump turn on and work.
And I am not sure about CEL In run position ill check that. no fuel pump noise either.
I will be checking compression today so I will let you all know what that tells me!
Thank you all for hwlping me out btw.

 

[samx227]

And no kunar, I have not messed with anything like that. I don't think its ever been taken apart up there.

 

[kunar]

i must have misread your post then, i thought you were getting fuel. given that fact, i think its pretty unlikely you have compression issues. obviously, the issue is in the fuel delivery, not cam timing. ill have to rethink this some...

 

[samx227]

Okay. Didn't get around to checking compression since battery died, and I have no jumper cables.. lol. So that will be tomorrow.
I'm just stuck on why the ecm isnt getting power!! Lol.

 

[samx227]

For some reason my compressiin tester doesn't fit my spark plug holes...too small. Anyways found no power to the injectors! Tested ignition module and its good. Looks like I may have the wrong fuel relay. The bwd one I got from oreilly/kragen has one more pin than the motorcraft one.. part numbers matched and apparently its the right one. Going to go to junkyard tomorrow and get some from other rangers/explorers with the same setup as mine and see what haPpens

 

[ab_slack]

Okay, this stuff is way over my head for the most part, but this comment "Noticed that when truck is put into accessory the cel doesn't come on for the quick second that it usually does.. " kind of jumped out at me.

I don't know about accessory position, but most lights come on momentarily with ignition on. What I always think of a "bulb check" time.

If it isn't coming on at this usual time, could it be that the bulb has burned out or come loose? I feel like I am stating the obvious so my apologies if it was checked and I missed it someplace.