Working on an 87 2.9L.

Truck sat for two years unused. I pulled it out of mothballs and have been getting it road ready.

It runs flawlessly for the most part.

When starting after sitting overnight, it starts but immediately bucks and kicks - runs fine - bucks and kicks - runs fine, and repeats for 5-15 seconds depending on the temperature. Never stalls. The colder it is, the longer it takes to smooth out. It runs perfect after this. You can cut it off cold after the initial jerk and shake, and then start it back, and it’s fine.

I am only getting an occasional KOER code 25 - knock sensor or something. KOEO is 11.

I have replaced the IAC, MAP, and have verified the ECT and Air temp sensor resistances are within specs.

Fuel was still good but has been replaced with fresh and driven about 50 miles. Flawless other than this start up issue.

I am wondering about the double fuel pump arrangement. I haven’t checked fuel pressure yet (need to get a gauge). What are the symptoms of a bad in tank pump (low pressure I understand)? Could my frame mounted high pressure pump be okay and pulling enough to cover for a dead or half dead in tank pump? Or vice versa?

Sucky video but better than nothing for those that can view it:


Ideas welcome.

Long time Ranger owner here. Have had my 95 since 2002. Love it. So slow 2.3. This little 87 is a hot rod on comparison 2.9/5-speed/traction lock in a regular cab custom trim no option (no a/c!).

 

I would replace the 2 wire ECT sensor, no way to test these reliably, and not an expensive part

ECT sensor sets the CHOKE, and if its voltage is show 40deg then 80deg then 40deg when cold it would do what you describe

You can cycle the key on and off 3 times before trying to start cold engine, that will build up fuel pressure to 30psi if it had dropped to 0psi by sitting overnight
Fuel pumps only run for 2 seconds when key is turned on, a safety thing, so turning key off and on 3 times will be 6 seconds run time which is about 30psi, and doesn't hurt anything, there is a fuel pressure regulator on the engine at limits pressure to 42psi engine off


In tank pump is a lift pump, so only 5-9psi, a carb fuel pump, the pump on the frame rail is the high pressure pump, to get 30psi at the injectors
If either pump fails you would get a No Start

 

I checked the ECT using the resistance method at Fuel Injection Technical Library » Engine Coolant Temperature Sensor (ECT)
It came back right on spec when the engine was cold. It also idles down very nicely once it warm up. Haven’t checked it hot. But I have an extra ECT I can throw at it. Can’t hurt.

I tried the key cycling as well. 3 cycles I think. Didn’t notice a difference but I will try it again after maybe 6 cycles on/off. Going to get me a helper tomorrow so I can listen to the pumps while they turn the key. Two pumps... seems like the bean counters at Ford would have not let that fly!

I have not put a new fuel filter on it yet.

 

The two pumps was because Ford already had the in tank pumps, they were for carb engines, so they used them up and then switched to the single high pressure pump in the tank

 

This truck had a new distributor put in it before coming to me.

Today I pulled the SPOUT. Problem solved.

Plugged it it back in. Bucking/jumping/kicking. Repeated just for check and got the same results.

I let it warm up with the SPOUT out and then plugged it back in. Idle raised a bit but no problems (never has been when warmed up).

I will check base timing with a light tomorrow and see where we stand. What does the 2.9 like for base timing?

And what would cause the computer to possibly go wonky on timing at start up?

 

Base timing should be 10-12deg BTDC, most prefer 12

Yes, could be computer as that is what the SPOUT wire is for, so the computer can suggest timing changes to TFI module for temp and throttle position

TFI module can do RPM spark advance on its own, but not LOAD timing changes, thats what Vacuum Advance did on distributors, and thats what the SPOUT wire and computer do, "vacuum advance" changes based on engine load which the computer calculates


You can pull the top off the computer, will look like this inside: Ford EEC-IV

You can see the 3 Blue Capacitors in the picture, these can leak after 20+ years and will cause odd issues
Under $5 to replace them if you can solder, and if they are leaking
Images here of that: Capacitor Repair: Ford A9L ECM « Moates Support

 

Thanks RonD for your continued help with this puzzle.

I set the timing to about 8 degrees initially. It was a little lazy to drive so I bumped it up to 12ish.

I swapped in an 88 ECM I picked up on Saturday. I heard magic things about it, something about ignoring EGR and knock sensor things. It did not change the behavior of the truck. I will crack it open and check out the caps.

I tried to check the timing with the engine doing it’s jumpy thing but it was off the scale. I really don’t know if it was high or low, or going back and forth.

The colder it gets, the worse this problem becomes.

I played a round of unplug the sensor (one at a time) and see if it makes a difference. Nothing made a difference. MAP, TPS, ECT, Air temp sensor, knock sensor. this was all with the 88 ECM. I cut it off between each sensor change.

By this point the truck had warmed up enough (2 minutes or so total run time) to behave itself.

I checked the TPS and it was at 0.9V to start with with smooth transition up to about 4.5V.

I haven’t swapped the ECT yet but it is on the to do list if nothing else turns up. I drive an 88 Country Squire daily that was been through two ECT’s and this truck isn’t acting like it did (poor cold drivability, low cold idle, high warm idle).

Additional ideas welcome.

 

Can I just plug in my new ECT to test it without installing it? Or does it need to ground through the ECT body? This is for a cold start up test only.

Could I also substitute it for an Air temp sensor temporarily?

 

Yes, as long as ECT sensor is at outside air temp you could test it that way, so leave if under the hood overnight or..................

No the threads do not need to be grounded


The IAT(intake air temp) sensor does use the same voltage resistance scale as the ECT sensor, but I think the ends are different, the part thats in the air or coolant

 

Tried the ECT swap tonight with a new sensor. No change :-(

IAT is pinned differently ECT so I wasn’t able to swap it out since I don’t have a spare.

Had an idea to run codes cold, while the problem was occurring. Only got the expected 21 and 24, and the same 25 I have gotten on occasion. This was KOER.

Going to try again tomorrow to get a timing reading to see if it’s retarding or advancing the timing. And check to see if I am getting spark during the cold run problem.

Am I right to assume that since this starts flawlessly with the SPOUT out, that the problem is the computer’s control of spark/timing and/or fuel timing?

I’m still referencing the fuelinjectedford.com site.
The truck starts without complaint. I think the “cold start” EEC strategy is working fine. RPM and ECT sensor in use, timing is TFI controlled, and fuel is preset.
We then go to cold start and warm up mode. Timing runs by “ECT multiplier”, fuel is preset by what I am assuming is RPM, and sensors in use are RPM, ECT, and ICT. I swapped the ECT... and checked the old and new ones, both spec okay on resistance.

The distributor and TFI, and coil are newer (on the truck when it came here). I am wondering if I have a bad PIP in that generic newer distributor.

No PIP means no spark? Maybe the timing isn’t just wonky, maybe it’s missing all together...

Thanks for listening to me think out loud.

 

Yes I would also lean towards computer issue on cold start

No PIP would also mean no fuel injection timing, so no start at all

The hall effect sensor in the distributor is the only engine timing there is, so TFI uses it for spark timing and then computer uses it for injector timing

 

Update: it’s a NO spark problem when it’s misbehaving. No wonder my timing light couldn’t get a reading.

Ordered a distributor with new PIP sensor. Will update once it’s installed...