Engine misfire possible ecu issue

[nreid90]

hello everyone,
new to the forum but i have had 3 mighty max's total in my life. my newest one a 1993 4g64 2wd 5speed was running great 2 weeks ago and now barely runs. if i pump the throttle after cranking i can get it to run but other than that it dies. I have a new mass air and coolant temp. those from what i read usually fixed the problem, but not in my case. it is getting fuel and the first o2 sensor was just replaced to pass smog in CA. i dont know if the trucks dont like after market parts or shat the hell is going on with this thing. please let me know what i can check or info you can offer. i am a technician but i dont have the service manual yet to help me test sensors. thanks for the help...

[finalfighter]

check fuses and all connections. check the connections on the passenger side firewall under the hood that are for the fuel injectors and distributor. also check the ecm and post a pick of the inside.

hope this helps

[nreid90]

All the fuses are good, the connections are good. the injectors are firing and so is the distributor but it seems like the injectors are not firing at the proper time. Its also puffing smoke out of the intake when trying to turn over. i will provide pictures as soon as i can.
thanks

[noahwins]

Check out the Haynes manual in this list, that should be good enough to get multimeter values. If you go up one folder, you can see the FSM for 4G6X engines. We keep our library organized in an alphachaotic order here at MR50.

http://www.mightyram50.net/vbulletin/showthread.php/811-Over-216-Manuals

[nreid90]

It seems like everything is in order. I have fuel, spark, timing belt is spot on, took the car off to see if it was clogged and still a no go.

[pennyman1]

alphachaotical? I like it...

[nreid90]

So I ripped it apart. The injectors are firing, the exhaust is not clogged, I have spark and the MAF is good. It has everything to run and it won't. The distributor is timed and so is the timing belt. The only thing I can think of now is the injectors are not firing at the proper time

[finalfighter]

check the ecm before doing anything else. i bet that's the problem

[DroppedMitsu]

Most likely some capacitors in the ECU have leaked out onto the board and messed some stuff up. Very common problem with these year vehicles

[nreid90]

So got the ecu this morning and the truck runs better but still no Bueno on running properly... Distributor maybe?

[nreid90]

Also I was trying to pull codes and nothing shows up my multi meter just shows the needle pulsing.

[geezer101]

I think that if you're not using an OBD type ECU scanning tool you have to count the pulses and refer to the service manual for codes. It can be tricky trying to pull error codes from the ECU this way but it works.

[nreid90]

Yes before I could count them but now it does not have codes it just sweeps constantly. And another new find. I put a clamp on my fuel return hose and runs better. Going to look at the feed and see what I find

[frenchy67]

Sounds like it could be fuel pressure regulator

[claych]

So nreid90,
What happened with this??? problem solved??? if not, update???
Just curious, as I put a stick pin on this problem to ck back.