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Thread: Fuel starved-can OEM electric pump block flow?

  1. #1
    Registered User rocketdog's Avatar
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    Default Fuel starved-can OEM electric pump block flow?

    The 260 has run fine (triple Webers) though infrequently. Drove fine last week. Today after hard starting (usual if it sits awhile) it ran rough then died. Lots of cranking and a few coughs of life but nothing. My first thought was clogged fuel filter. Sure enough it had junk in it so put in a new one. Unscrewed the fuel line pump to carbs and had fuel from pump go directly into a plastic bottle. Did get some fuel ( but didn't seem to be a lot) but connected everything up and the car started but didn't run well after a while and then died. Unhooked line from tank to filter and drained about a quart. Fuel looks fine. Tried again to start but same symptoms: Runs awhile then dies like not enough fuel. If the OEM electric pump is faulty (or plugged) can it impede flow? My thoughts are to bypass the electric pump and use only the OEM mechanical as it should be enough for the Webers as it has in the past. Comments?
    Late 260Z; 2005 Daytona Blue paint; Triple Webers 40DCOE; competition springs w/Tokico HP shocks; Koenig 17x7 Crosshairs w/ Yokohama AVS 215/45 WR 17; Original owner; Show car w/ many awards

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    Registered User madkaw's Avatar
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    Have you checked the banjo bolt screens at the carbs? If you found dirt in the fuel-it made it to the carb?
    Filter screen at electric pump?
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User rocketdog's Avatar
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    Success! Banjo screens clean. Disconnected the fuel line at the electric pump and the mechanical pump and blew out the line....just in case. Then connected the outlet from the fuel filter directly to the hard fuel line bypassing the electric pump. After serious cranking to get fuel up front she fired up and ran flawlessly. Still need to check out fuel pressure issue and gauge only reading 2 psi. I do have a fuel return line with regulator but it never seems to do anything. I will block off return line this afternoon and see what pressure is. I'd like to be 3-4psi. Hope the mechanical pump isn't wheezing out. Haven't tried car under load yet as is on jack to get to rear pump and filter. The filter at the electrical pump may be plugged but bypassing was way easier than taking that thing all apart. Per all the threads here and other sites I don't really need the electric pump.
    Late 260Z; 2005 Daytona Blue paint; Triple Webers 40DCOE; competition springs w/Tokico HP shocks; Koenig 17x7 Crosshairs w/ Yokohama AVS 215/45 WR 17; Original owner; Show car w/ many awards

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    Registered User LeonV's Avatar
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    I had a similar issue, removed the crappy OEM pump, and all was well running just the mechanical pump. This is on an L24 with triples.
    2/74 260Z

  5. #5
    Registered User Stanley's Avatar
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    Might want to put a filter in line where the electric Fuel pump was. Yesterday took out the clear filter I had there, put a metal WIX can with 5/16 barbs, also put a USCG rated marine 5/16 fuel line from the filter to the hard line at the frame. It's lined so the ethanol crap can't touch the rubber, and has a 2 1/2 minute burn rating, 8 bucks a foot but you only need a foot.

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    Registered User rocketdog's Avatar
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    took out the electrical pump and checked the filter. Sloshed it around in gas and some crud came out but not enough to plug it. It's the original so 39 years......... Blew dry it with compressed air and stuck it all back onto car...mostly for the bracket so I have someplace to anchor the plastic fuel filter. Did not reattach fuel lines to it. Did plug the return line at the carbs and now I'm 4-5 psi vs. 2psi with return. I would suspect that with the electrical and the mechanical running together there would be more pressure as I was getting 4 psi with both when the return was used. If I remember I think with the return plugged it was too high like 6 or so with both operating. Car runs fine.

    Anyway big local car show tomorrow, only a couple of miles away. 10/5 I go to the All Datsun Show in Winslow, AZ 3rd Annual Multi-State Datsun Classic (75 miles for me). Certainly don't want to croak in the boonies on I40. Great show with pre 1985 Datsuns only....lots of old roadsters.

    Found a new problem tonight. After detailing I started her up to pull into the garage. Decided to turn the headlights on. Dash lights didn't work till you hit the high beams. Anyway started smelling smoke from electrical so turned them off. Another project, another day.
    Late 260Z; 2005 Daytona Blue paint; Triple Webers 40DCOE; competition springs w/Tokico HP shocks; Koenig 17x7 Crosshairs w/ Yokohama AVS 215/45 WR 17; Original owner; Show car w/ many awards

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    Do the headlight relay upgrade-you will be glad
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User rocketdog's Avatar
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    One year update: I reinstalled the OEM electric fuel pump. I've been getting some fuel starvation and possible vapor lock this summer. After hard acceleration through the gears, once in 4th it starts cutting out till enough fuel gets to the bowls. After sitting and heat soaking at a store I get stumbles the first 1/2 mile or so after leaving. My pressure gage reads 3-4 psi when cold but hot it fluctuates between 1 and 3. I don't think my mechanical pump is putting out enough so I reinstalled the electric pump today. Cold or hot I'm now getting 3-4 psi and no fuel starvation after hard acceleration. I did have a minor stumble driving through traffic accelerating from a stop light. Temps about 90 today. My mechanical pump might be weaker than spec. I've studied all the posts covering aftermarket electric fuel pumps, but want to avoid the hassle of the wiring and inertia cut switches and redoing/adding SS braided fuel lines.
    Late 260Z; 2005 Daytona Blue paint; Triple Webers 40DCOE; competition springs w/Tokico HP shocks; Koenig 17x7 Crosshairs w/ Yokohama AVS 215/45 WR 17; Original owner; Show car w/ many awards

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