oinkinstein

Heres a little background info, my 1993 P/U with a 22re was throwing a code so i checked it using the TE1 E1 thing and got a 25 which i have gotten before, the last time i got it i just cleaned the AFM and it went away so this time i did the same thing, unplugged the AFM harness and took the AFM out cleaned and inspected it and put it back on. When i go to start the truck it turns and turns and turns and wont start. I ordered a new AFM thinking i may have accidently ed it up and it still does the same thing after installing the new one. My friend told me it may be the ECU and told me to do another diagnostic check. so i jump the terminals and to my surprise there is no check engine light, no OK signal constant blinking or anything, it doesnt even blink once. So is this a sure sign of a bad ECU? thanks guys

scuba

I would think yes.

What happens without the jumper when the ignition is on ?

bugs1961

If the Check-engine light isn't coming on with the ignition switch on but the truck not started, then you may have a fuse blown that powers the warning system. Check the 10amp Gauge fuse.

You can download the FSM here: http://www.ncttora.com/fsm/index.html and troubleshoot using a volt/ohm meter. After you download the manual find the procedures by:

1. Open EG1 folder
2. Open MFISYSTE folder
3. Open TROUBLES.PDF

This section will step you through troubleshooting the ecm and the various sensors providing information. The terminal of the ecm that sends the signal to the check engine light is "W" and is the bottom row, second from the right as you look at the back of the ecm (leave the connectors connected while testing). If the "W" terminal tests good, you probably have a bad ecm. The ecm hardly ever goes bad unless it's opened and tampered with, or given a voltage spike through a short or reverse polarity at the battery, so there is usually another cause.

If you can use a digital multi-meter give this a try before buying a new ecm. Take care,
Bugs

scuba

ORRR, You could just go here.

http://www.personal.utulsa.edu/~nathan-buchanan/93fsm/

abecedarian

Well, an AFM should not keep the engine from starting. Many people here have disconnected the AFM and the engine still starts, but dies after a few seconds.

Jumper the Fp and +B terminals in the diagnostic connector and see if it will start. If it does, it's not likely to be a problem with the ECU.

TomThumb

There is a Fuel Pump Switch in the VAF(Volume air flow meter). Often referred to as an AMF. Its a secondary circuit that closes to turn on the fuel pump when the engine is cranked and the little metal flapper in the VAF moves. If this switch is damaged or fails the truck will not start. Like Abecedarian said Jumper the Fp and +B terminals and if the truck starts you need a new VAF> Had the same issue with my 91 pickup.

oinkinstein

i tried jumping those 2 in the diagnostic box and still nothin. it just cranks and cranks and cranks. i smell gas too so i dunno. this is baffling me and im on an extremely tight budget after getting laid off and this whole thing is really frustrating. any other suggestions? im sure we'll be able to find out the problem collectivly

J.z.

chech cold start injector take out 2 10 mm bolt's gently pull out csi .Put fuel pump jumper in . Crank motor(I usually a home made remote starter switch. Battery to switch to small starter terminal). If no spray from CSI check CSI time switch no