Need HELP 1991 F150 Truck Eng wont start (runs no power)

[SPIKER]

Hi All:

Needing help getting this truck going.   last time I drove it (Sept) it Started & Ran OK but when Driving it it seemed to get weak but made it back to farm.

Spec. 1991 F150 2whl drive with 300 6 cylinder, multiport fuel injection 5 speed manual. 

It will start with spray of ether and once running stays running but idles low & rough.   I've gone thru most of it already still same issues.

NEW Fuel Pressure Regulator (both fuel pumps run continuously) Pressure in the rail is 55PSI dead center where it should be.

I cleaned the plugs and wires & cap all good spark seems good on all 6 cyl.   The plugs were carboned up from running rich but only have about 25K on them.   

It has Check Eng light on but I cant get it to test/dump codes for some reason (guessing the ECM or my tester is bad?)   

Any thoughts on best way to test the Injector Banks to make sure BOTH sets fire?  think this thing has dual injector firing pulses alternates 3 & 3 per cycle/thanks

Mark

[james]

check your cat converter too much back pressure will do that also
james

[SPIKER]

James thanks, I dont think  it is cat clogged.   the exhaust dont get HOT and the engine does REV UP which with a clogged cat they typically wont REV at all.

Mark

[shelbycharger400]

Hey spiker..
Do you have a timing light?

I don't know much bout fords, I tend to stay away from them!
Not shure where it is on ur engine harness, but it has a  2 pin connector into this grey plastic block, you pull it out for setting base timing. I have heard of these falling off or are loose.
They call it a spout connector.
If that engine is stuck in base timing, its going to be doggy!
How many miles are on the clock?  those motors are known to run for 300k +  I drove one once with a 3 on the tree, it had over 300k, and NO power lol.

[SPIKER]

Hey Shelby:

The timing jumper is just off the side of the distributor / coil harness on side of the engine.   I have not checked it yet.

ENG only has 118K so barely broken in.   uses no oil has new water pump, about 3 months back put a new alternator on it, the power wire fell down against the exhaust manifold shorted out and melted wires up pretty good.  burnt out the diodes...   Not sure if that might have started anything wrong now only has maybe 100 ~ 150 miles w NEW alternator charges good now and has good voltage.

[Handy Andy]

 I have an old truck with 300 ci 6 cyl, it has a carburetor, so different, but similar.  I just replaced the fuel pump as it was running but weak. Finally just would start but would die after a few seconds.  First I replaced the fuel filter, that didn't do it so replaced pump.  Runs great now.  Fooled me, because the pump worked, just didn't have enough pressure.

[KyLogger]

Might be the crank positioning sensor, I know it's a different beast but my 99 POS f 250 service truck had a similar problem, but it finally started one day and now I drive it with absolutely no power 8)  it's the biggest piece of junk vehicle I have owned!

[Al_Smith]

You'll do yourself a favor if you just get it hooked up to an analizer .That thing has a zillion inputs to the EEC modual .You've got a MAP sensor ,PIP signal ,O2 senser ,knock sensor and  a dozen more I can't remember .Which is odd because I did the electrical work on 40 "hot test " stands for years used to hot run the engines in the engine plant prior to shipping .

Now if you have a good library you have access to the very best technical books I've ever seen are put out by Mitchels .They tell step by step how to diagnos problems on just about every engine made within the last 30 years using common testing equipment .

For that matter places like Auto Zone ,Parts America  , maybe Pep Boys will test the components for you free of charge .

If you get to just swapping parts on a hunch you might end up spending a fortune you don't have to .

After thought : It could very well be the EPROM modual it'self which is inside the EEC modual .If it fails it has a "limp " mode which allows the engine to run just not very well .That modual can be tested also .

[Al_Smith]

Now the basic engine itself ,the 300 I6 is probabley one of the toughest engines ever made .It has a good track record although in some cases it gets swore on a lot especially the later versions .

The carborated versions such as my old '77 F-250 are almost bullit proof but the design is simple .It has an early EEC system which did fail on me and was replaced at about 150,000 miles .That old rust bucket now has over 250 thou on it but it's getting a little tired .It's semi retired to the woods .

[shelbycharger400]

al beat me to it on the eprom.    That is a definate possibility as to why you have issues trying to read codes too.   anytime you melt wires, You will have future issues!

[SPIKER]

Hey guys:  so ya say autozone can test EPROMs?   I can pull the computer (power train modal looks pretty easy to get at.)  have to pull inner kick panel and few bolts.   (lost my 10mm wrench on last visit to PULL-A-PART) swore I had it coming out but wasnt there right after getting back to put on the pulled parts GGRRR   

It sure is getting aggravating as usually I can get something going with just a few cus words and a bit of duct tape or epoxy putty...

I'm going out after it tomorrow with 5 gal of K1 for the torpedo heater and hopefully more energy...    also going to help nephew on his Dodge Dakota blew out his 3rd transfer-case...

Mark

[shelbycharger400]

only autozone can test your computer while it is in the truck
Orileys , you can " rent" a scanner, they charge your credit card the list price, you bring it back, they credit your card back

[SPIKER]

Shelby:  that is what I thought, not sure but think my trucks comp is the issue as my code reader wont hook up and the meter test procedure in the book got nothing from / out if it...

Mark

[shelbycharger400]

Your next step is check powers and grounds to the pcm. if they are all good, not grounded out ect and you have no feed data,  then usually it is a pcm

[SPIKER]

Hi Guys:

Worked on it for several hours today,   still same issues I dont have a NOID light and could not find my O-Scope leads (it has not been plugged in in over 10 maybe 15 years so not sure it will even work anymore it was a 20 buck unit donated to the local school.)

I Pulled #1 plug confirmed TDC and Timing Mark, cleaned distributor cap pins and rotor, re-adjusted the distributor after pulling the jumper to set timing to off.   Re-adjusted Timing to ~14degrees it was retarded about 5 deg.   I pulled the plug to the distributor and re-inserted checking for possible corrosion no change.   

   Plugged jumper back in no change would not start, took a shot of ether to get it going would not start without it and still similar issues timing stayed the same throughout the RPM range & under quick throttle response I get no advance from the distributor advance.   SHOULD have had an advance...

The PCM was next to look at so pulled the connector and re-inserted it to see if there were issues w the plug, did the same with the Fuel Pump Relay and PCM Power Relay, no change...   SO pulled out the PCM it is in the trunk ready to head to junkyard for a replacement..

Still thinking it is SO aggravating not being able to FIX the dang thing....   Thanks for help so far. 

I didnt look closely at the grounds on the truck/battery side will take a closer look there and will also put a meter on the injectors individually looking for shorts...

thanks guys

[SPIKER]

Hi ALL:

Well I got back from Junk Yard local (40 miles each way to Pick-a-part) with a 22 bucks for the PCM got it installed and started right up...

With Key on fuel pumps run for 10 or so seconds and shut off (one of the indications there was an issue as pumps didnt shut off.

SO lots of frustration but got it running. I've worked on cars & trucks a LONG time first time I've had a ECM/PCM failure where the vehicle would still run and 1st ever on a FORD...

Thanks for all the help ya all!

[grweldon]

Great price on the PCM.  Would be about $150 here.  Glad you got it running!

[SPIKER]

GRWELDON:  'ya the PICK-A-PART or PULL-A-PART are pretty great places clean organized and set pricing so you dont have to feel like you are getting hosed with like new prices for a part ya pull yourself...

Mark

[millstead]

I agrea with grweldon said that was a great price around hear we have a you pull it junk yard and they charge you to get in then there prices are way to high I bought a distributer there and it was cheaper to buy a new one from auto zone. Glad to hear you got it fixed

[SPIKER]

the LOCAL junkyards are like that pricing is pull up autozone and cut the price 10% for their pricing that is why I went 50 miles each way to Pull-A-Part http://www.pullapart.com/ there are others that are similar too "Pick-A-Part" was one I used to visit our in CA 25 years ago which was probably the precursor to the ones I hit now...   Our local salvage yard is only concerned with metal scrap and grind up $1000.00 worth of car parts for 40 bucks in metal.???  they are idiots in that respect. : ???   Remember going there for a few parts few years back and it was more expensive than NEW part for a used Nissan trailing lnik they were 25 bucks at dealer and the junk yard wanted 30 or 40 bucks (link looked like a bolt about 8" long with formed sheet steel)  the dealer part was 2 week delivery so I took off for junkyard...   took 3 hrs to pull the part off junker and guy had a fit that I only wanted to pay 20 bucks... : >:(   He said It cost him more for his guy to monitor me pulling it Not my fault it was rusted on took what it took and it was worth what it was worth not more cause it took extra to get off... >:(

Mark

[blades]

Sounds kinda like an injector shorted possibly in the open mode, if it smells like it is running real rich likely that is it.

[SPIKER]

Hi All:

this week I managed to find time to pop the top on the FORD PDU/Computer.   There was/is two Caps (47uf) that are bad/popped and the electrolytic goo leaked out of them.   There are a couple pics I have posted off the FF site
**Note from Moderator:  All pictures must be in your gallery**

the pic quality was not all that great as it was my Cell.   

The last page above details that the thing is Probably fixable but the board is fully conformal coated for moisture resistance.   that would mean a lot of cleaning to get the coating off & then replacing the CAPS and then re-testing the thing.   With this thing fixed I'm not too worried but for someone without the cheap junkyard parts this could help them find & fix their own PDU/Computer.

Mark