305 TPI hard starting.
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Joined: Aug 2015
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305 TPI hard starting.
OK, I'm sue there's a million of these threads, but none of them seems to be exactly like my issue.
I just bought a '86 IROC with the 305 TPI. It had this issue when I bought it and I'm trying to figure it out. It starts hard when cold and if its hot and you go to drive it again, say 15 mins later it won't start and I have to let it sit. I've checked fuel pressure and the pump doesn't run with the engine off/key on. Key on/ engine running at idle it stays at 40psi and holds it when I put the car in gear or rev engine. When I shut the engine off fuel pressure drops pretty quickly. It takes a few seconds to build pressure in the line too. When it does start I have to feather the throttle to get it to do so. Do I have a bad pump or regulator or something else? Leaking cold start injector?
Thanks
Matt
I just bought a '86 IROC with the 305 TPI. It had this issue when I bought it and I'm trying to figure it out. It starts hard when cold and if its hot and you go to drive it again, say 15 mins later it won't start and I have to let it sit. I've checked fuel pressure and the pump doesn't run with the engine off/key on. Key on/ engine running at idle it stays at 40psi and holds it when I put the car in gear or rev engine. When I shut the engine off fuel pressure drops pretty quickly. It takes a few seconds to build pressure in the line too. When it does start I have to feather the throttle to get it to do so. Do I have a bad pump or regulator or something else? Leaking cold start injector?
Thanks
Matt
Joined: Nov 2008
Posts: 2,097
Likes: 177
From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: 305 TPI hard starting.
Key on/engine off the fuel pump should run. Possible problem with the fuel pump relay. ....see diagram http://austinthirdgen.org/mkportal/m...ine_wiring.gif
If there's a problem with the relay circuit, the oil pressure switch is a back up, so you need to crank the engine to get oil pressure to activate the fuel pump circuit. I'd start there.
If there's a problem with the relay circuit, the oil pressure switch is a back up, so you need to crank the engine to get oil pressure to activate the fuel pump circuit. I'd start there.
Thread Starter
Junior Member
Joined: Aug 2015
Posts: 2
Likes: 0
Re: 305 TPI hard starting.
Key on/engine off the fuel pump should run. Possible problem with the fuel pump relay. ....see diagram http://austinthirdgen.org/mkportal/m...ine_wiring.gif
If there's a problem with the relay circuit, the oil pressure switch is a back up, so you need to crank the engine to get oil pressure to activate the fuel pump circuit. I'd start there.
If there's a problem with the relay circuit, the oil pressure switch is a back up, so you need to crank the engine to get oil pressure to activate the fuel pump circuit. I'd start there.
I got this car for $600 cheaper than the seller's listed price because he thought it needed a new pump. A little research and a $17 relay later...FIXED! The seller claimed he was a mechanic too. LOL
Thanks!
Joined: Nov 2008
Posts: 2,097
Likes: 177
From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
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