Dear all, please help me. My '81 308GTSi was converted fuel injection to carb. A few weeks ago, the fuel line had pin hole and she was nearly burned. So I canged all the fuel lines and the fuel pump from injection type to carbs to remove the regulator and make the fuel pressure low. But this might cause the trouble. She runs fine till 2000rpm, but above this rev like 3000 to 5000, I feel lack of gas and she starts caughing and at the last, she stops. But after a while, like a minute, she starts again. My opinion for this frouble might cause by the difference of the breather pipe of the fuel tank. Is anybody have any idea for this situation. Any words will help me. Thank you very much.
I take it you have the correct pressure for the carbs from the fuel pump. I am not familliar with a 308 venting system but generally you have a 1/4" (or so) line go to a catchcan type deal, then a line from there to a charcoal canister and from there a line back to the carbs. How is yours rigged? Ken
If you think the breather pipe is too small causing a slight vacuum in the fuel tank, drive car with fuel cap off in straight line. That eliminates possibility of vacuum forming. Have you checked the fuel filter? Did it ever run properly after the conversion but before the hole in the fuel line?
thank you both of you I will try to run with the fuel cap off. Will post the results later Image Unavailable, Please Login
Do you have a ~2 mm diameter orifice restriction in the return fuel line from the carbs going back to the fuel tank? My guess would be that your earlier high-pressure injection type fuel pump with the regulator set-up would have so much extra capabilty that it wouldn't need (or even want) an orifice restriction in the return line; whereas, the "wimpy" carb type fuel pump needs the restriction in the return line to help keep the pressure up -- just a thought if you don't have one...
A couple of thoughts.... I find it impossible to believe that the car was converted from FI to Carbs and the pump was not changed. Carbs do NOT like 30+ psi fuel pressure no matter how good the return line is. I suspect that the fuel pump you had was a carb one. What sort of pump do you have now? It is probably not able to flow the correct rate and pressure. Also check your filter..... If they get clogged, then the flow rate will be fine for gentle running, but WOT will drain the float bowls causing exactly the symptoms you describe. If you are not sure what pump to use, get a Holley blue. Probably much cheaper than an OEM pump and generally considered a great electric pump for carbs. Just my .02 Dave
Had a similar problem on my 79 308. Fuel starvation was caused by the check valve (single directional valve) beside the fuel pump. It was just bypassed and the fuel line was rerouted. You must retain the recycling route of the gas. I was told that the valve was a safety device required by the Italian Gov. When the valve was removed you could not blow through it. Before removal 1 psi fuel pressure after 4 psi. Worth checking out.
