Mazda B2600i Nightmare! - Mazda Forum
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post #1 of 6 (permalink) Old 05-09-2018, 05:42 PM Thread Starter
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Mazda B2600i Nightmare!


I am having big problems with my 1991 Mazda b2600!
It starts just fine, runs for about 10 minutes than it just dies!
it will not start at first but after 1-10 minutes it starts and runs like a dream until i stop it and it cools down again, than it is the same prsedure all over again every time!

I have tried 3 different ecu`s and one of them has been repaired two times with no luck.
I have changed just about every electrical part in the engine compartment, but it seems to have no effect on the problem...

My car does not have a lambda.

I think it has something to do with the car switching over form warm up mode to working temperature mode?
what do you guys think?

pleas help!
have any of you had simular problems?
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post #2 of 6 (permalink) Old 05-12-2018, 05:03 PM
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Won't run when warm

Not familiar with your model, but the problem you describe may apply to other makes/models. If you have an electric fuel pump it may be crapping out when it gets warm. Have you checked the fuel delivery volume and pressure in the won't-run condition? Another *guess* would be that there is a temp sensor out of spec and the combination of a failed ____ sensor and having no O2 sensor might be enough to cause the no-run situation.
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post #3 of 6 (permalink) Old 05-14-2018, 08:22 PM
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It could be the pump as RichieP has suggested. However, a more common failure is the sensor inside the distributor. There are three common ways for them to act up:

1. Fail completely and the truck will never start again without spark and or injector pulse.
2. The sensor will start failing when hot. After cooling down 30 minutes to 2 hours, the truck will restart and run fine, like you describe.
3. There is a seal in the distributor. When it starts failing, it allows oil, or oil vapor to enter the electronics components on the distributor. This may cause a temporary failure / intermittent operations, or if bad enough, it might not start at all.

I think you might be experiencing situation 2 or 3. I would take the cap off and remove the cover inside and look for any signs of oil. Even if it is just a thin film of oil, it can fog the optical sensor and cause you to not get spark or injector pulse.

You can also try putting a timing light on it while trying to crank it when it has warmed up and died. If you don't have spark, then that could also confirm the signal from the distributor. But it also could be coil or igniter related too. Even better would be to get some noid lights and install one or two on an injector harness plug and see if the injectors are being commanded to fire while the engine won't start. If not, then this is even a better indicator that the distributor is at fault - since it provided the signals for the ECM to fire injectors and spark.

Also check the condition of the wires where they enter the distributor plug. The connector is known to fail but sometimes the wires start breaking where they enters the plug. Make sure yours looks good.

You can also get a fuel pressure gauge and check the pressure. There are several tests to run on the fuel system to make sure the pump and regulator are working properly. You could have a clogged filter on the firewall, or the sock (filter) on the pump in the tank could become clogged with debris (often rust). Sometimes the engine will starve for fuel when it is the intakesock. After sitting for a while, it will release some of the debris and then start sucking it up again and clog agian.

And of course, like Richie said, the pump could be getting hot. But I doubt it would get that hot in 10 minutes since it recirculates the fuel back into the tank - especially if you are in the cool weather of Norway!
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post #4 of 6 (permalink) Old 05-15-2018, 01:09 AM
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The nightmare problem I had with my 93 B2600i ended up being the distributor. I think some of my posts are on this site (unless they got lost with a web site problem or something). In process of trying to get to the bottom of my problem, I got the engine computer refurbished, a new MAF sensor (or was it MAP sensor? - it was a big thing that the intake air goes through), a new ignition module, I cleaned and inspected some of the wires, and maybe a few other things before removing the distributor, which had a cap that looked normal to me, but the distributor itself even I could tell was bad when I removed the whole thing and examined its internals (some internal parts were so delicate they disintegrated upon touch - and I thought 'it's a wonder the truck had run at all'). Once I got to the distributor, pretty much by process of elimination, I was surprised it had not been more difficult to understand the instructions in my Haynes manual about how it needs to be oriented for the timing to be correct. And I bought a timing light gun from HF and checked and/or set my idle speed also at that time.

My nightmare problem defied 2 mechanics who I paid early on to diagnose it, which surprised me and reduced my confidence in them. The engine computer mail-away refurbishment service and MAF sensor were the result of those two diagnoses. Doing those things was putting up a lot of money for such an old truck (though the engine computer refurbishment seemed to help some and that may not all have been my imagination). After those two high-dollar failures ($200-$300 total) I decided to take the time to think about and observe the problem carefully each time it happened, looking for hints, posting and reading the info available on this forum. Somehow I came to believe it was an electrical problem and got around to inspecting the distributor (after months and months if I remember correctly).

Like yours, my main symptom was unpredictable stalls and the engine's failure to start for a while afterward, which became less and less predictable over time. On another vehicle ('97 Chevy Astro) I'd had a plugged fuel filter cause a stall that would clear by waiting a while, but that wasn't my B2600i's problem. I'd had the engine rebuilt, but the distributor wasn't a part that was replaced at the time and the problem happened a few years later (at about 220,000 miles, 25k or so after the rebuild). That problem was maybe 5 years ago and I'm happy to report that my B2600i is still running well and that I'm glad I didn't give up on it, though pressure built to do so as it was parked a lot and, when used - which was necessary to obtain further clues - sometimes caused trips to be disrupted, resulting in waiting until it would start again or leaving it and getting another ride or walking. It became enough of a frustration that before it was fixed some family members began referring to it as junk, having simplistically concluded that it had a problem that was just impossible to solve. Eventually my persistence was vindicated and I hope you have a similarly good result!

Last edited by OldMazzies; 05-15-2018 at 01:18 AM.
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post #5 of 6 (permalink) Old 10-15-2018, 12:53 AM
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your temp sending unit located by the thermostat do a oms check with your multi meter also do a volt check on volt setting on your volt meter. or you have a bad grounded Ecm run a separate ground wire to your Ecm most times this is your problem.just google checking your temp sending unit.
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post #6 of 6 (permalink) Old 12-31-2018, 07:10 PM
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I read many complaints like yous with intermittent missfire or starting problems and wonder why nobody mentions the heat sink gel which dries out on back of ignition module. This gel is at least needed to properly dissipate heat from the ignition transistor but sometimes is also needed as a ground connection. Ive worked on several of these trucks and every time I see a new one I always find the gel dried out. The ignition module has a metalic backing for a reason.
I suggest anybody with spark or start relating issues take care of this routine service issue first. I use copper anti sieze compound on them.
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