Messages

It's not the injectors unless you passed alot of crap through the lines. You already stated that you had 2 filters so I doubt that you passed enough stuff to plug an injector. I don't have a clue about the sd computer. Did you make it far enough to get a code reader and see if you have codes?

Still don't have a code reader......
My assumption on the clogged injectors is that I bought this engine out of a junkyard and that maybe it sat there a long time and the fuel went to varnish.  Maybe they are original injectors and have never been cleaned.  Is this possible?  It will not start now but it will fire a few cylinders upon first crank then nothing.  Just  a little fuel getting thru ??

OK,   it has 42 psi  of fuel pressure at the rails.   That means fuel is getting to the injectors and I've already confirmed that it has spark and earlier this week it would run for a few secs.   So my diagnosis is that the injectors must be clogged.  Right wrong or can a fried computer make it not run at all ?      The fuel pump still runs all the time and when I unplug the computor it does not run at all so pin 22 is stuck at ground.     I'm nervous about putting the speed density back in ........ could it hurt anything other than the computer itself ??   Or should I shop for another A9P  ??
Looking for advice???

the ford uses teh same size fitting as a tire... but they sink the core in deeper..  be sure to have the cap on it...when not testing ... i have seen a few cars that burned when the fuel leaked from that... probably do to improper poking at it to test fuel pressure...

most auto parts stores have the fuel pressure tester that looks like a compression tester but it has a clear vinal hose also.. this is to blead off fuel pressure safely.. the kits come with the proper adaptor...


there are trouble shooting charts for every item in that system... i take it you have printed these out...   the wife has boxed up all but a few of my manuals....
here another link with codes on it.. and how to access them

http://www.autozone.com/az/cds/en_us/0900823d/80/19/4c/96/0900823d80194c96/repairInfoPages.htm

did you look at figure 6 of the link i sent ...?

Yes I looked at figure 6.  This was one of the diagrams that I used to rewire the engine swap. It was taped to the wall over the work bench.
Keep the advice coming.........I'm still learning.

Harbor Freight sells a $15 kit that has a gauge and a tee and some hose that you can use if you have hose in the system somewhere. If you have the schrader valve on the inlet, you would need their higher priced kit. I don't think it is common for a regulator to be stuck open. If it's possible, check the return line for flow. It the reg is open, you'll have quite a stream of fuel. I'd start with finding out why the pump relay doesn't shut off after the initial key on. That makes me nervous.

Yes need to find out why the fuel pump won't stop.
Fuel system has a schrader valve.
I can't see the return line easily,  and can't really tell by any sounds in the fuel tank.  Will get a fuel pressure gauge.....what would a tire pressure gauge do on the schrader valve

One question - when you rewired to use the MAF, did you add the wire that goes from the fuel pump to the computer to monitor it (FPM) on pin 19?

Leon
Yes I added the wire from pin 19  to the fuel pump power side.  I'm surprised that the computer monitors this way,  with only reading 12 volts.  It really should read oil pressure to know that the engine is running,  or monitor the tach line or ignition.    
Pin 22 is the one that provides ground to the fuel pump relay to turn it on.  I don't know why it is now always ground,  especially when two days ago it was working correctly and only turning on for a few secs   I don't  have an extra  MAF  computer to try,  but do have a speed density computer and  .........what would happen?  If I cook the speed density ....so what.

did anybody back probe the system with a test light?>>> the transister driver in the ecm blows out at 1 amp....   sometimes using aftermarker relays without diodes to dampin the high voltage spikes that can be generated when the ecm opens the circut...and the magnetic field collapses in the relay....

are you anywhere near los angeles..

i have several eec 4 break out boxes... got a otc at a swap meet and a rotunda from a scrap truck where a ford dealer threw it out...

Wayne
No have not probed at all. I do have a digitable multi meter and will be using it but haven't yet.  Yes you are correct about the spikes,  they can blow a transistor or logic circuit,  that is part of my job at work, we put diodes in mil spec connectors for aircraft and military equip just for that reason.
I am using an aftermarket fuse / relay box from Bussman,  but it uses automotive relays that have the diode.  The relays are the smaller GM type that are rectangular.
I may have a computer problem as the fuel pump does not shut off like it did previously,  but I think I have a fuel problem that is causing the non start. Tonight and weekend I will get a fuel pressure gauge and check that back.  There is a coarse filter upstream of the fuel pump and I can see gas in it,  but the fine fuel filter after the pump is unknown.  Yes the flow symbol is pointing correctly.  Could the fuel regulator be stock open and cause all fuel to go back to the tank?  Could the injectors be clogged enough to cause no start?  Don't know how long it sat in the junk yard.

OK  now I'm really wishing I'd done something different.
Tonight the fuel pump runs non stop,  whenever the key is on.  Last night it worked properly, ran 2-3 secs when the key on and then stopped.  It just sat all day..........no one around.  And it doesn't really start now.  It will fire once when the key first turned but not really run like it did last night.   Bought the noid light and yes the injectors are opening,  light flashes bright.   Checked the spart at the plugs and good there.   So it's got fuel (injectors opening), spark, timed  what gives???
I have an extra computer but it it is a speed density   AOD2 ,  can I try it just to see if there is any difference?
Next will buy a scanner and check the codes.  Or has the computor died and that is why pin #22 of the computor is grounding the fuel injection relay all the time??

The truck ignition switch is not yet in the wired system.  I'm holding the harness that goes under the dash (all new that I've wired)  and have not yet hooked it to the key switch.  Just touching wires together to start / run.

I do not have a check engine light and don't see it on any of the schematics.  I do have the MAL  function connector wired in.  It is same an all wiring diagrams that I have so it must be correct.  I do not have a code reader for it.  Next thing to buy.....  So  don't know if it is showing any codes.

Yes the computer scans every time the engine starts. It scans continuously after that. When I was sorting out problems on mine, I found out about the 2 second interval. The fuel pump is run by one of the relays in the system. If you had switched power running to it that was disabled after the key was released from the start position, you would have the end result you are describing. I assume you have a good wiring diagram?

The fuel pump relay is on switched power,  but the computor has both always on  and switched according to the NUMEROUS  wiring diagrams that I have.  That is a sore point.  I must have a half inch of printouts that I'm working with.  Most are the same,  but minor little things are different and  they say for a particular year of Mustang 5.0.   The computer is a A9P  and yet I don't know what year it is other than 87  to 93  or so.  (Ebay).  I had to make up the harness from two  or three other harnesses as I have components in non std locations and am running the MAF  on the inlet.  Tonight I'll try the noid light' as Wayne suggested, and see if the injectors are staying on.   If they are not then what New computer??

It will start again if I turn off the key and do the same again.  Can do this as many times as I want.  Does the computor still scan?  I do have "always on"  12 V  to the computor.
Will pick up a noid light on the way home tonight  and will borrow a meter from work.

does the fuel pump continue to run once the truck starts...    you might try a hot wire directly to the pump to see if that will let it run... the ecm only powers the fuel pump for 2 or 3 seconds as soon as you turn the key on to charge the fuel rail...

it depends on a differnt circut toget the ecm to continue the power to the fuel pump relay, main eec relay and the fuel pump...



this link should be close to what you have look at figure 6....

http://www.autozone.com/az/cds/en_us/0900823d/80/19/59/5a/0900823d8019595a/repairInfoPages.htm

when you look at it.. both the fuel pump relay and the main relay have to be on  for the fuel pump to get power.... figure 5 does not look right.... in the eec main and fuel pump relay wiring...  that is probably because there was some probems in the factory diagrams in that area earlier.. made my life tough for a few hours a long time ago...

Yes the fuel pump does continue to run and then stops about 3-4 secs after the engine quits.   So there is fuel being pumped to the rails.  Earlier, before I had the wiring done, I had "hot"  wired it direct and engine did the same,  ran for a few secs only.
How does the fuel pressure regulator work?

Been working on this 71 Ford pickup for 6 months and got the 5.0 HO running tonight sorta.  Spent the last 6 weeks rewiring for the A9P computor to run the MAF and all other stuff.  All factory stock,  but no smog pump.  Did keep the EGR system.
Well it fires immediately and then quits in about 3 secs.  It is running out of gas.  I know this because if I switch the key on and off numerous times and fill it with fuel it runs another fews second longer.  If I hold the start on when it is stalling it will still not keep running.  Is the computor not opening the injectors or is it something with the fuel pressure regulator seeing vacuum and then dropping the pressure too low?
Injectors can't be clogged with old gas could they as it always starts ??

There is an old junkyard out in the desert that I frequent and I "think" there is one of these old specials there.  Should be out there in about 2 weeks so, ping me about then and I'll try.

There is no fuse in the relay. I fuse  the control circuit, and use a beaker on the load circuit.

It might pay to mention types of fuses and  breakers here. Fuses for the most part, come in two types. Normal, and slow blow. you would want a slow blow fuse where you have a high initial load, which quickly drops to a lower load. Glass fuses blow slower that ATO/ATC fuses. Computers normally use a fast blow fuse. Heater blowers, and other motors, use slow blow fuses, unless you are using a relay.

Breakers come in several types, fast blow, slow blow, self reset, and manual reset. If the circuit you are protecting would be damaged if energised suddenly, use a manual reset breaker. Something like power windows with a momentary switch can be protected with an automatic reset breaker.

In the main power wires, I use a fusible link, or a Maxifuse. This will protect the entire system. A Maxifuse is easier to replace.

I'm planning to use a max fuse for the main power,  but need to buy one.  The factory harness (Ford) that I've been cutting up has a 175 amp max fuse and to me that seems like waaayyy  too much.  Car would be in flames before it blew.
thanks,  will put in fuses as I already have them and the fuse box.

Just finishing off a project and putting in the relays and notice that I see relays used a lot and yet little or no fuses.   Do see a lot of fuseable links but
Do the auto relays have built in fuses and if you pop one then you just replace the relay?  Most relays are rated for 25  or 30 amps  so if you exceed that in a short does it burn open the contacts or ? Am using the GM type D4227 is one set of numbers and 12088567    D00   are the other numbers.  They are rectangular relays about 5/8  x  7/8  by 1 inch high  with just 4 contacts.  What is the amp rating of this one?