JhnRX7

I have been having some intermittent issues lately. Mainly sputtering and hard start when hot. Well yesterday I think the fuel pump finally died, The sputtering got really bad when it was hot out and the pump started making some very terrible loud screeching sounds.

I had a pump lying around that came off of a turbo model so I swapped them out. It successfully fixed the issues I was having, however it also created a new one.

Now, in order to start the car, I have to turn the key to the on position to cycle the fuel pump. I have to do this twice before the car will start normally. Once it starts, it runs great.

Is there any reason that I should not be running a turbo pump on my NA? Does the turbo fuel pump typically get fed a higher voltage than the NA? If so, would having a lower voltage not be giving the pump enough power to prime the system?

JhnRX7

The only difference I noticed between the two pumps was the outlet.

The NA pump had something in the outlet nipple (see picture) Some kind of check valve maybe? There is a piece inside of there that physically slides up and down. However the turbo pump did not have this... Any idea on what this is?

snwbrderphat540

the turbo pump is capable of flowing more gas and at a higher psi.... CAPABLE. it will however not create an issue. for some reason it sounds like your car isn't holding very good pressure though and thats why you need to run the prime cycle twice. might have a bad FPR i would stick a guage on the fuel feed line (rubber hose that leads TO the fuel rail not after the fuel rail if that makes sense) and get a reading on it.

280zx2by2

when the last time you changed/checked your fuel filter? it could be clogged

JhnRX7

Thanks, I attempted to do this today, however my cheap-o harbor freight fuel pressure gauge leaks (alot) so i don't really trust its sporadic reading. Need to pick up a decent fuel pressure gauge.

Fuel filter was replaced about 6 months ago. But when I changed the pump i checked the fuel that came out and it was pretty dirty. when mixed up it was a light brown color. The gas tank is only a few years old so I really hope it is not rusting the fuel lines are all original tho so they might be the culprit... Regardless i'm changing the filter asap.

snwbrderphat540

also, i know in the S30 there is a plug on the bottom of the tank you can take out and drain all the crud out with then maybe sprinkle some extra gas on through to flush a little of the left over debris (dont waste gas but gotta do something) and then get a new filter up in there. that or just drop the tank and spend an afternoon cleaning it out the proper way. also, you can just make a your own very good guage out of some house hold plumbing. just get a T fitting (all brass) thread in a water tank pressure guage in the top of the T and 2 nipples on the sides that would be the proper diameter to match the fuel hose, dont forget to teflon tape it and WALA!

duowing

Do you have a fuel pressure gauge? This isn't an uncommon issue. Alot of these pumps being older have seen some kind of crap go through them. I'm sure the non-turbo pump has it too, but under the outlet nipple, I believe it unscrews, is a check valve. Some people have had where some junk from the tank gets stuck and doesn't allow the check valve to hold pressure in the system. So it bleeds off fast and can require cycling the pump a few times to build pressure. This is another reason why people see the hot start issues. The check valve doesn't function correctly so more fuel bleeds back so it's easier for the fuel in the rail to vaporize.

This may not be the issue, but after alot of reading on zcar.com I've seen that this is enough to cause an issue. A fuel pressure gauge can sometimes tell you this. If you stop the car then immediately try to restart it, does it start back up fine?

JhnRX7

See the picture in my second post. Is this the check valve you are referring to? If so, the turbo pump that I installed did not have this at all...

duowing

I've yet to actually look at the check valve myself, so I'm not sure if that's it. It could be. All I remember was that the picture you show, that piece could be unscrewed to gain access to the check valve. Maybe you could take the two pumps apart and see? If the one has a check valve and the other doesn't maybe you can swap the valves and solve the issue?