240z lost power, could airtex 8012s electric fuel pump be damaged?

[jalexquijano]

my 240z was running nice the other day. it accelerated fine. However, after bringing it back from the shop where they replaced the master vac brake booster, master cylinder and differential mount, the car had lost power and if accelarated it started backfiring through the intake of both SU Carbs. i asked him "Did you changed the idle mixture knobs or touch the carbs anyway? He replied no. I guess he left the key on accesories with the fuel pump running and the engine off. Do you think that even though the Clear fuel filter is full the fuel pump could have become damaged?

 

This will be the third fuel pump i change for this car:

 

Airtex 8012sx electric fuel pump which pumps 5 to 9 psi at 30gph as advertised on Summit Racing website.

 

Any other better pump than this or should i get rid of the MR GASKET clear fuel filter as it may be restricting the flow? Which fuel filter is non restrictive and recommended for high flow?

[datzenmike]

Any fuel filter will work, just get one that fits. Not a bad idea to filter the fuel before it enters the pump too. Most after market pumps advise this.

 

 

Third pump says there is something wrong with the choice of pump or the set up. Electric pumps use the fuel flow to keep them cool. A stalled fuel pump will over heat. Most external electric pumps are on a relay so that when the engine stops so does the pump. External pumps should be mounted as low and close to the tank as possible and never in the engine bay. All pumps are good at pushing but struggle to draw fuel vertically and through fuel lines. 

 

I know that the early Z cars had mechanical pumps and there was an electric.... maybe as an option? I don't know if both were used together or not, with one supplying the other? Maybe to make room for the air conditioning pump?? The pump should be self regulating and when the regulated pressure is reached the pump shuts off or slows. That said running them with the engine off may over heat them as the fuel flow through them cools them also.

 

Have the fuel pressure checked at the carbs with the engine running. If in doubt, and can afford it, replace the pump. The Hitachi SUs are sensitive to over pressure, so find one that is regulated to 3.5PSI or get a separate fuel pressure regulator.

 

Change the filter first though and see it that corrects the problem. It's cheaper.

[HRH]

Run the stock mechanical pump.  It works absolutely fine for dual SUs.  If you're going fuel injection, get a fuel injection pump.  When I had the 510 and the hi-comp 2.0 LZ20 long rod, I had dual SUs and a mechanical pump.  Never had one issue.  You will have to change them every 30-50k though.  Rubber diaphragms only last so long.  But, cheap and easy.

[jalexquijano]

Well actually i am using an AIRTEX 8012Sx electric fuel pump which appears to have a Steel filter. Any other better Brand or pump than this one? I did noticed it is connected to the accesory at the ignition switch. In order for it to last where should it be connected?

[jalexquijano]

Well just replaced the pump with a Brand new one! At first the car was still having problems on accelaration presenting some backfire. I pull the 6 spark plugs out and clean them with a brass wire brush and contact cleaner. The car still lacked power and was backfiring at the intake of the carbs. Sincé i had 3 spare Brand new NGK BP6ES spark plugs on the glove box i replaced spark plugs 4, 5, and 6 (rear carb) and power came back. I did tightened all the screws of the braided hose that go to from the valve cover to the vac brake booster.

 

Do you think this NGK spark plugs get so fouled that even after cleaning them, they become useless and you need to replace them???