Electric Fuel Pump Diagnosis

[Mike]

Hi all,

Who makes the best electric fuel pump for the early Z's? I noticed that Motorsport Auto has them either new, rebuilt, or performance types.

Are the MSA rebuilt pumps any good?

I ended up removing this pump over the weekend. When I connected 12v to the thing... it did nothing. So, I pulled it apart and twisted the gear manually. I think it was stuck. After I moved it, I added 12v and the thing took off. It went back together just fine and I tried to pump fuel through it while out of the car.

No go. Fuel didn't suck out of the bucket like I was expecting. So, I figured that maybe it needed to be 'primed'. I put it back on the gas tank and held the other end of the hose near a bucket. Nothing.

I can hear (and feel) the pump turning in my hand, but, it doesn't suck or push fuel. Is this a bad pump?

My original thought is yes. But, maybe there's something I need to do in order to get this pump to work right. Can anyone help?

Also.. When I remove the fuel line from the tank to the pump... should gas fall to the floor? I mean, should it flow to the ground by gravity? I drained the tank and put in 5 gallons. But, maybe it's plugged?

TIA.

[m]

[mike graff]

I have a 71 240 which I allowed to sit for too many weeks

without starting. I know that there is a leak in the piping from

the exterior filling hole

to the gas tank, for if I put in more than about 12 bucks worth

at the filling station, gas comes leaking out.

Anyway, I tried to start the last few days, and put

three gallons in. After turning the engine over for quite a while,

it still did not start.

I assume that all of the gas had indeed evaporated.

I dissconnected the gas line at the fuel filter, and

turned the engine over, hoping to see a spurt of fuel,

but nothing.

Is there some kind of method for priming that I should be

aware of? Or is it more likely that the electric pump has

frozen up?

Any help would be appreciated.

Thanks,

Mike G

[kmack]

Are you sure you have an electric fuel pump? 71's did not come w/ an electric pump stock, so if you pulled the gas line from up stream of the mechanical pump then you won't see any gas come out.

Normally gas does not evaporate quickly, at least not in large amounts. 3 gallons of gas will take a few weeks to completely disappear. If you just want to make sure the engine will fire, run a fuel line from a gas can to the mechanical pump and try to start the engine from that.

As for the hole in your tank, I wouldn't be surprised if the long, 1/2" diameter vent line hose on the left side of the tank is cracked or broken. That would be the first thing I'd look at when seeing a fuel leak from under the tank. They are relatively easy to replace and there has been a rather extensive discussion on this site about it.

If you do have to replace the vent lines, then now would be a good time to clean up your tank a little and blow out the fuel lines.

BTW, are you planning on making it down to San Antonio for the National Z Convention in June?

[2ManyZs]

Mike, it sounds like your pump is shot. It should prime itself, it evidently will pull a siphon but won't pull the gas out of the tank. That is probably why the gas siphoned out when you unhooked it. I have one if you are interested. E-mail me and I'll tell you about it.

FWIW, I have been doing business with MSA for almost 20 years and have never had a problem with anything I got from them. By the way, is this for your 280? See the price on the pumps??? OUCH!!!

[Mike]

Ya, this is for my 280z. It has a pressurized system which requires a special fuel pump. And, hell ya.. I saw the price of that pump, it's over $200!! One of the local dealers quoted me $239. MSA is $199.

But, they have a rebuilt option for $99. That's the main reson I was asking about MSA. I wanted to know if their rebuilt pumps were worth a $^!#. Most rebuilt items (in this critical of a position) I've found to be less than adequate. IE: they fail after a very short time, or just don't work at all.

With a critical element like this (and the fact that it's a messy job to replace), I'll probably buy a new one.

Thanks for the info.... I wasn't sure if it created suction on its own upon initial start up.

Another question, do you know if the tank is supposed to drain if I remove the hose from the tank to the pump? It's a short hose (about 3-5" long) and mine just leaks a little fuel.

I figured that the tank would drain out of this hose as soon as I removed the fuel pump. But, maybe it needs suction. ?

[Mike]

You guys know of a good method to inspect a gas tank while it's installed on the car? I was thinking of a video-inspection-scope of some kind. Sorta like the one at your dentist... that would be PERFECT!!

[mike graff]

kmack,

Thanks for the reply. You know, I thought '71s had two fuel pumps: a mechanical one at the engine, and an electric one back near the tank. But maybe I was looking at a diagram of a 260.

What a blessing to find others out there with similar experience!

I'll try your suggestion with the mechanical pump and see if

it's moving fuel tomorrow.

I'm a neophyte Z mechanic, so this forum really helps.

As far as the San Antonio convention goes, I might get down there. The last Z function that I took part in was at the

Texas Motor Speedway when Nissan had re-released the

refurbished 240s. It was just a few weeks after I'd bought mine.

A hell of alot of fun.

Best,

Mike Graff

[Mike]

Mechanical fuel pumps are fairly inexpensive. If you seem to be having fuel problems, get a new one. The diaphram inside can deteriorate over time and won't give you the fuel you need.

[m]

[Zlishous]

I have a 74 260, and I know that they had a manuel (front) and electronic fuel pump(rear), my question is: my rear one was taken out at some point by someone else, is it a good idea to replace the electronic or is it not really needed? Iam going to autox with pretty much a stock engine so I am not sure? anyones thoughts would be appreciated!

[kmack]

Zlishous,

If by "stock" you mean the stock '74 carbs, then you may want to put an electric pump back in your car. The late '73 and '74 carbs were the whole reason for the electric fuel pump (along w/ the mechanical) in the first place.

If you're going to be running SU's then you won't need to worry about it too much unless your carbs and/or engine have been modified and will require a greater demand of fuel than the mechanical pump will provide.

[Zlishous]

No, i already have SU's in her, so you answered my question! Thanks! But, what mods would require re-instillation? Comp cam??? I am a newbie so I am learning as I go. Thanks again!

Zlish

[kmack]

I would recommend an electric pump if made some or all of the following:

L28 block and head with larger valves

Race cam

fuel injection

turbo

weber carbs.

If you just swapped in an L28 block, let's say, you could probably get away with the mechanical pump only if you're running the SU's. But since that engine already came with an electric pump (because of the fuel injection) it would really be a good idea to install one. No sense in running the risk of running out of fuel and causing a lean condition which would hurt the motor. Especially while you're racing. If you're only running the stock L26, I wouldn't worry about it too much.