Need help with fuel issues...

[Mat M]

If I'm reading this right you've got two pumps in the system which seems a bit crazy to me.

Why? MANY people have been using an electrical fuel pump (including myself) to augment the mechanical. The less restriction for the mech pump, the easier it will be to keep up with the fuel demand at 5-6 thousand RPM.

When you switch on the ignition the electric pump will be trying to push fuel to the mechanical pump which will block the fuel until the engine is running. ...snip...

Yes, BUT that's what the float bowls are for. That is the extra fuel supply untill the car has started. As Beandip correctly stated, when the motor is running, every time the lever on the mechanical fuel pump gets actuated by the cam (750 times per minute at idle), the pump will push fuel.

This is why I suggested a tear down of the mech FP, to ensure that the diaphragm is not ripped, effectively pumping fuel into the block (as Beandip alluded to earlier) and to ensure that the one-way valves in the pump are still functional.

[Nigel1943]

Yes but this guy has'nt even got the fuel to the carbs yet so what I'm suggesting is a way to get fuel up to the carbs with the least restriction. Still can't see the point of two pumps. The stock mechanical pump is perfectly adequate for twin SU's.

[SuDZ]

Why? MANY people have been using an electrical fuel pump (including myself) to augment the mechanical. The less restriction for the mech pump, the easier it will be to keep up with the fuel demand at 5-6 thousand RPM.

As far as I know this is how the 260Z came stock.

This is why I suggested a tear down of the mech FP, to ensure that the diaphragm is not ripped, effectively pumping fuel into the block (as Beandip alluded to earlier) and to ensure that the one-way valves in the pump are still functional.

Ok as far as an update, the car did turn over and run for a second when I sprayed some starter fluid in. I was psyched even to see that and called my girlfriend out to the garage (so she would believe me hehe) and when I started it there was a huge puff of black smoke that came out over the engine. I'm not sure where it came form though but it only lasted like a second.

Afterwards I poured some fuel into the inlets and it started for a second again. I am going to try to get a new elec fuel pump since that one is dead after I tested it. I will replace that and tear down the mech one to see if that looks clean or not but it is tough to get at since I will have to remove the AC compressor. So if I get that pumping and running off of that then I will take it from there. I figure this way I can get a regular amount of fuel constantly coming to it from an external canister and see if it will run for more than a second worth of fuel.

I am going to try that next. Seeing the car even turn over like that after 4 years or so was so exciting. This definitely gets me in the motivated mode again to get things going again.

Thanks for everything and I will let you know more as I go.

SuDZ

[SuDZ]

STUPID 5 MINUTE EDIT RULE!

I meant, if you didn't have fuel at the bowls after a while of cranking the motor, then you would be right to suspect the mech. F.P.

The hard part is that I don't have SU's. They SU from what I have read (never seen any in real life) have external bowls that you can see easily. The carbs I have are built in so you can't really see them without removing the carbs I belive. Considering how dry the lines were though I know they were not getting fuel to them.

SuDZ

[wfl_colorado]

I haven't read the entire thread, but did you try a coffee can w/ gas in it and feed the tube coming off the fuel filter into it and see if you are getting any suction as all? I had an issue w/ mine and it didn't work correctly until the fuel filter actually filled up w/ gas. It was like the suction was getting bled off or something.

Bill

[sleepyzzz]

I had seen that pump also when I was cruising the MSA site. Is the benefit of the new pump just the fact that it's newer or does it actually perform better somehow? If it doesn't need to be replaced just yet I will hold off. I guess testing it tonight will let me knows whats what.

SuDZ

my car has been sitting for twenty years without being run. i didn't want to chance that old pump letting me down while out cruising once i finally get mine back together. after spending almost $160 for the Holley pump, i found one alot cheaper with the same 5.5-9 psi specs at a local parts store for $38.

[SuDZ]

I went and picked up a fuel pump last night. I am going to try to hook it up tonight for a test. I am thinking that I will fill up a can with the gas and hook the fuel pump up after the mechanical one right where it would be feeding to the fuel rail. I will see where this gets me and if it will fire up or not.

I picked up an after market fuel pump from Autozone but just didn't have a chance to try it out yet. This seems like it should let me know what's going on one way or another.

SuDZ

[SuDZ]

Well here is the update. I'm still stuck. I have hooked up a fuel filter to the hard fuel lines after the mechanical fuel pump. I get gas all the way to the carbs because when I pull the lines the gas comes pouring out no problem. It still won't turn over though. It gets to about the same point as it was earlier to tell you the truth. The fuel now is getting to the carbs but won't turn over.

I read in the repair manual that I can inspect the float level with an inspection mirror which will tell me if gas is getting there I guess. I just don't know where it would be going otherwise.

I'm getting low on some ideas to check next...

SuDZ

[Mat M]

OK, here's what you do next.

Find yourself a trebuchet (http://www.ripcord.ws/plans/plans.html). Remove the flat tops, place said flat tops into basket of trebuchet and pull the trigger wire.

I have a set of roundtops that work. PM me if you are interested.