Rough idle and stall running on petrol?

[lynrick]

G'day,
I have a 94 model 1FZFE 80 series on LPG and petrol.
Been having trouble with running on petrol the last few months. Has got to the stage where it stalls on idle when running on petrol. It runs perfectly on LPG (idling as well). Indicates no electrical problems.
When I first noticed the problem I thought the injectors were dirty so I ran a few tanks of injecter cleaner through the engine but this didn't help. Approached my mechanic and he said to start with the injectors so I had this done professionally. This didn't help at all except that it let more fuel through and the engine blew more black smoke at close to idling revs. (Too rich a mixture.) Did some research on IMud and a few guys were talking about the cleaning of the MAS. Bought the appropriate Isopropyl Alcohol to do the job ($60 AUS, 1 litre) and soaked overnight. Dryed and refitted. This improved the running of the beast and I was extremely happy with myself. Drove to work about 40kls and it performed flawlessly, idling happily at the 30 or so traffic lights I was caught at. 5 minutes from work it stalled at traffic lights again and so it was on again! Injector bloke thinks it could be a problem with the Coolant Temp Sensor or a Fuel Pressure Problem. My mechanic and I have ruled out the MAS. He got a hold of a spare unit and fitted it. Vehicle behaved exactly as previously.
Has anyone any ideas?

Gett'n fed up!

 

[fjdaveinoz]

Dirty fuel or blocked filter? Dodgy Fuel Pump?
If its running on LPG, then it has to be something directly related to the Petrol Side of things,

Dirty MAS, cracked intake hose, coolant sensors etc, will result in poor running on both fuels.

Id be checking Fuel Pump, as they fail, particularly if not being used (ie if you run on lpg a lot and dont use petrol) but start with some clean fuel, as it does go off quick

Dave

 

[lynrick]

Thanks for the ideas, Dave. I have a new fuel filter to fit but haven't been game to tackle it. P**k of a place for it! The MAS is OK but I am having the mechanic checking the fuel pump and associated fuel pressure. Injector guy also mentioned the coolant temperature sensor. Do you know where it is located? Might replace it if it's not too dear.
Richard

 

[lynrick]

My mechanic has fixed this problem. Turns out that the MAS can be adjusted by taking the black cover off the top. Apparently there is an adjustment for cold running and one for hot. It's a bit of mucking around to get it right but it certainly worked.
All the research I've done in forums, I have never come across any info on adjusting the MAS. has anyone else?