Gutless 95 GQ Dual Fuel

Submitted: Friday, Feb 04, 2005 at 16:56
ThreadID: 20111 Views:1807 Replies:5 FollowUps:2
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Greetings all, my 95 EFI Dual fuel GQ runs great on gas, and has heaps of power on Petrol when the engine is cold but when the engine warms up it's really gutless.(petrol only). It's best described as the same flat spot you get with a sticky/stuffed fuel plunger in a carby but doesn't clear. You put your foot down and it hesitates and doesn't "un-hesitate".
New fuel filter didn't fix it.
Good cold, bad warm....any ideas?
Scott
Sorry for the poor explanation
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Reply By: Truckster (Vic) - Friday, Feb 04, 2005 at 16:59

Friday, Feb 04, 2005 at 16:59
Plugs?
Plug leads?
Dissy?
Timing?
Rotor button fubar?

Have you done anythign to the engine in the way of servicing it?
Did it just start, or gradually got worse?

Bit more info.
AnswerID: 96676

Reply By: Brew69(SA) - Friday, Feb 04, 2005 at 17:20

Friday, Feb 04, 2005 at 17:20
Fuel pump? Shouldn't be anything to do with spark if ok on gas. Also check timing as truckster suggests. Timing set ok for gas will not be optimal for petrol.
AnswerID: 96682

Follow Up By: Ferret - Friday, Feb 04, 2005 at 18:13

Friday, Feb 04, 2005 at 18:13
Yeah, thought about fuel pump but it goes a treat when it's cold. What settings are different with an EFI engine when it's stone cold that would see it run fine cold but flat when warm.
Scott
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FollowupID: 355374

Follow Up By: Member - David 0- Friday, Feb 04, 2005 at 18:21

Friday, Feb 04, 2005 at 18:21
Depends on how sophisticated the system is. At the very least, there is a thermistor measuring engine temp (coooling water) and also fuel temp and sometimes air temp. If these go haywire you could conceiveable run into a problem that you would notice, though I wouldn't expect it to be as noticeable as u describe.
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FollowupID: 355375

Reply By: Member - Jimbo (VIC) - Friday, Feb 04, 2005 at 18:18

Friday, Feb 04, 2005 at 18:18
Tuning could be a factor.

LPG has an octane rating of over 100 and ULP is 91. If it is tuned perfectly for LPG it will be poorly tuned for ULP. Is it pinging running on ULP?

For an engine tuned to run on LPG, it is adviseable to run Optimax or similar with a RON of 98.

Not suggesting this is the problem, but could be a contributor.

Cheers,

Jim.
AnswerID: 96686

Reply By: Member - Jeff M (WA) - Friday, Feb 04, 2005 at 18:45

Friday, Feb 04, 2005 at 18:45
If it's hesitating I would be guesing that it is overfueling or flooding. How does the EFI and LPG Conversion work? Are they independant of each other? If so maybe the ECU is not working very well at all (maybe sensors,injectors or anything really) and the gas is working fine... Therefore if that's the case you need to ignore anything to do with it being an LPG conversion and start troubleshooting as if it's just a petrol powered motor.

Have you tried running some injector cleaner in the fuel? Do you run it on ULP regulary or not at all?
AnswerID: 96693

Reply By: Splitpin - Saturday, Feb 05, 2005 at 01:45

Saturday, Feb 05, 2005 at 01:45
I have a gq patrol diesel and a celica GT4 (which is currently for sale i might add), but the celica once had a similar problem to what your patrol has. I tried heaps of different things to fix it and i was sure it was something to do with the fuel. So the first thing was the filter and that did nothing. Then I took the injectors out and had them cleaned and let me tell you that was the biggest pain! its like they sat the injectors in the middle of the factory and built the whole car around them! So then i thought maybe I had water in the tank as it had been raining for weeks. Had to take the whole tank out as they have no bung in the bottom, so there was another day wasted! In the end all it was was a humble set of leads "D'oh" I had to tell the guys at work it was an injector so they wouldn't take the p!ss out of me.

I guess the moral of my story is try all the easy stuff first before you go doing open heart surgery on your vehicle. Your leads may be breaking down as they heat up because an increase in heat means an increase in resistance and they may then be just arcing straight to the head like my leads were.
AnswerID: 96742

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