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Astrovan cuts out inexplicably

we have a 1995 chevy astrovan. Some days it runs just fine and then others it cuts out repeatedly when we slow down or brake. It?s been to the mechanic a million times and he can?t find the problem? Please help!

I would start by checking the fuel pressure. If your van has the Vortec V6 with central fuel injection, which I suspect it does, you need around 60 psi for it to work properly. A failing fuel pump will not be able to provide this, and these vans are kind of notorious for failing fuel pumps. A failing fuel pump will create the intermittent symptoms you are experiencing.

The first 2 things I’d be looking at are the idle air control (IAC) valve and brake booster. But you’re going to need to give at least some clue as to what the mechanic has already done/checked/etc. Its actually fairly annoying to have these posts where people start making suggestions and then we later hear “oh, that was already done…” So save everyone a lot of trouble and give all the info you have.

In addition specify whether or not there is a check engine light and, of so, what error codes have been obtained.

There?s been no light. I?ll call the mechanic and ask what?s been done and repost. Thanks?

If this vehicle uses a type of fuel injection called CMFI (Central Multi-Port Fuel Injection) there are a host of issues that GM says are tied to poor quality fuel. CMFI is the injection type that uses the “spyder” and poppet valves. I think it is certainly possible your vechile is CMFI equipped but I also know some other vehicles with the 4.3L engine used electronic multi-port injection. Ask your mechanic the fuel injection type used and if he says CMFI ask if he has made use of the published data to aid in repairing CMFI vehicles.There are quite a few drivability TSB’s published and the range of fixes suggested is very wide.One even calls for a better designed PCM (#67-65-37).

So the mechanic says that he has cleaned the valves, changed the spark plugs, changed the seals on the valves, cleaned the fuel injectors, changed the air and gas filters. There have been and are no lights going on. He also says he checked the brake booster and the idle on the air control and it?s neither of those, He also checked the MAF sensor. I (obviously I?m sure) know nothing about cars and am translating the names from Spanish, so I may have got some wrong.

He says he thinks 60 is way too high and that it?s about 35-45. Is this climate/altitude related? We live in a hot part of Mexico… apologies in advance if that?s an offensively dumb question.

He says it is CMFI, how would I go about finding the published data on how to fix it? Thanks!

Are you a student? does your schools library contract with EBSCO? that is how I get a look at TSB’s. Another way is the library or a one car subscription on AllData I think AutoZone has some type of service. There is probably a half a dozen ways I did not mention.

Keep in mind that TSB’s are only hints at what could be wrong but they are very helpful espically when the car has been looked at so many times with no postive result.

It is good when you can put in make,model,year and look at every TSB rather than having to know the number of a paticular TSB.