Will not Rev after 8 Years!

Hello all, my name is Martin from Bucks, UK.
Wondering, can anyone give me some advice, tried the UK Owners Sites and no joy so far. I have a 91 GTO Twin Turbo. It was off the road for 8 years until I rescued it. My third one owned and worked on. So far I have drained Fuel Tank, replaced Fuel Filter. Full 60k Service, Belt, Pulleys Plugs, Leads and Vac Hoses amongst other things. It starts and ticks over OK but when revved, it pops and bangs and hesitates, just will not go onto Boost. Rechecked today, Timing, Plug Leads on correct, sprayed Carb cleaner and can not notice any engine change. Can not see any vacuum pipe problems. I don’t know if it could be connected but it looks like my Alternator may be shot, on an old battery ( waiting for new one to be delivered) it’s only showing 11.8 Volts with Engine running! Can any one give me any advice, thinking now Coil Packs but I don’t know if I can check these before replacing, again, any advice?
Many thanks for reading and if you can help it would be much appreciated? Stay Safe.


Start with a good battery and check alternator. A low voltage will mean that the ptu will not switch properly and the coils will have a low output. Then check the ecu and fuel pressure. Old fuel pumps tend to stick and give low pressure. Never waste money on a coil pack. Each coil can be easily tested and you only need to replace the faulty one. Look at the running engine in the dark to see if there is any arking from poor leads, coils or plugs.


Thanks Joe. New Battery is on its way. I’m still thinking Alternator has a problem due to only showing 11.8 Volts at Tick Over. Fuel Pump has been replaced and also Fuel Filter and the Fuel…

If your checking the alternator output at the battery terminals you should have a minimum of 12.5v because that is what your battery voltage is. If you are only getting 11.8 volts it would suggest to me that you have a cell gone in the battery. I wouldn’t do anything with the alternator until you have a decent battery fitted when you should get between 13.5v and 14.5v. As Joe says if you don’t have the correct voltage various components wont operate as they should.

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Thankyou Gazzz, getting a little list here!

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FOR INFO … Coil Pack Testing tip - Video ( Not Mine )

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If l was you l would open the ecu and check the capacitor condition.

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Yeah, I think I’ll do that tomorrow, battery is taking for ever to get here!

A little update. Took the Alternator to a rebuilding Company expert and they Bench Tested it, found no problems, all working correctly.They suggested the problem is the Cable from the Alternator to the Battery. Something else to do tomorrow!

Hi, would 4 AWG Car Battery Cable/ welding cable be suitable to connect my Alternator to the Battery? Seems this is my problem!

Don’t know about a welding cable, but I do know of a guy who used an old set of jump leads, mind you, they were pretty heavy duty, but it did the trick.

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I had a similar problem with my 93 Stealth tt. It would start and idle ok, but as soon as I pressed the accelerator, it would lurch and RPMs jump all over the place. I thought it was a fuel pump/filter issue too. Turned out to be a bad capacitor in the ECU. Once repaired, it ran perfectly.

It is highly unlikely that such a high current cable would be faulty but it is very common for the end connectors to break down due to corrosion, oxidation and poor fitting.
The ECU is still my bet.

Hi again, just back from my Garage, replaced the Cable with new and Battery is now charging at 14.6 Volts and …fingers crossed…seems to be running correctly. Not MOT’d or Taxed so only taken it up the Farm Track but seems to run and boost OK. MOT Booked for Monday, here we go again!

Oh dear, thinking I may have a problem with this. At the back of the Alternator are 2 Heavy White/Red Cables that I have now disconnected but only one of these goes back to the Battery, where does the other go as it now has no Power from Alternator. The Car “seems” to be running OK…help, MOT tomorrow!

A little update. One of the Sites suggested it was not right! I’ve now connected the 2 Cables from the Alternator to the Fuse Box, it’s then a single cable up to the Battery. A lot less risk of a Fire if it goes wrong!

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