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Stumped on a B-2600


michael_k0
08-19-2005, 01:34 AM
I'm working on a 90 b-2600 for a friend and have a very strange problem. It has the 2.4 fuel injected motor with 150,000 on it and it will not run with the gas line connected. I work in a shop and have access to all kinds of diagnostic tools, manuals and Alldata. All of the specs are in range, but it will not start or run with the fuel line connected. It initially had 85 Psi at the filter, I pulled the regulator and it was stuck, I cleaned it and it is working right now. The only way I can get it to run is if I pinch the fuel line and get the pressure down to 5-10 psi, anything higher and it floods out and dies. The truck has had fuel tank problems before and it was towed from another shop that supposedly flushed the tank. I checked the plumbing diagram and schematics with Alldata and it looks right and there are no restrictions in the lines. Any Ideas would help. Thanks, michael

Kyrasis6
09-06-2005, 09:59 PM
Sounds to me like an injector stuck open. Does it diesel if you cut it off after its fully warmed up? What is your O2 reading? HC ppm on the gas analyser? Have you tried unplugging 1 injector at a time and starting it with the line at normal pressure? What about trying to start it in clear flood mode by holding the gas down while cranking?

Perhaps a weak injector, causing it to function normally at low pressure but at high pressure it is forced open?

Do you guys have an ignition scope or a good O-scope? You should be able to see any bouncing of the injector pintle in the voltage reading. You should probably find one of the injectors have the voltage fluctiate before it closes or it will have low flyback voltage because it is not closing.

Might just be able to stick a screwdriver up to each one and listen for one that doesn't click as hard or as often if at all.

Of course the fact that it has a 2.4l engine in it is instant proof that someone has seriously played with it before as it should have a 2.6l engine in it and carbureted unless it is a B2600i.

michael_k0
09-08-2005, 12:40 AM
Thanks for your input, We have found out from the owner that he bought it not running, we have a snap-on scanner, but we usuually don't work on junk like this and we dont have the interface for the diagnostic connector. It's just a b-2600 and has many hands under the hood, there is no telling what has been done to it. I suggested parting it out or lighting it on fire and rolling it into the lake, but the boss won't go for that. I'll check the injectors and see if that's it, thanks again, mike.

mazdatech177
09-08-2005, 03:22 PM
sounds like your pcm has shot its wad.... it hangs the injectors open. its a fairly common problem on these. and i think we have reman pcm's now, so they shouldnt be too expensive....

michael_k0
09-08-2005, 10:31 PM
How much, when and where?? I tore everything apart today and checked the injectors, everything was spraying OK, The only thing I haven't tried is the PCM, I'm really sick of this truck and I need to get paid for the work I've done. I'll try a pcm, if you have one you know is good, make me a deal.. The truck is a 2600i, but it has a 2.4. Mazda is all Japanese to me (except for the rotary, I've had 6 RX-7s). thanks for your reply. mike

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