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  • Running fuel pressure

    got a fuel pressure gauge today and read the manual which states that standing fuel pressure should be between 38-43psi with the engine not running and vacuum hose off, i have 38 with the ignition on. Engine Running it states that when you reconnect the vacuum hose to the regulator it should drop " a little" , my fuel pressure at the test port with the engine running is only 32psi and i guess its not adjustable as stock, i have a new filter i will fit tomorrow but wondered what it should be with the engine running and the vacuum hose to the regulator connected?

  • #2
    anybody got any ideas?

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    • #3
      Fuel injector flow rates are based on a base pressure of 42.5. So that is a good number to go by with the vacuum hose unplugged. Once you put the vacuum hose back on, it should pull down to 38, roughly.

      Back in the old days, it was common to get an adjustable regulator and turn up the pressure as a safety factor to over-richen the fuel mixture. But once the technology came along to actually modify the fuel control, that tweaking was no longer valid.
      -Brandon

      Race cars are like strippers. They only work when you throw money at them!

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      • #4
        Thanks Brandon, ive swapped the fuel filter out and now got nearer those numbers with it running but still not seeing 42.5 so i guess ill have to swap the pump over now, i wonder if my mrs fancies wrestling with the fuel tank :-) . What ever happened to this other old site? Whenever i google any info about the car i get heaps of links to a site ending with .net that seemed to be filled with all the info i need but its not there anymore ?it would be a shame if all that information has been lost forever, I'm trying to check the base timing as suggested by Eric but my timing tab is rusty and there is no way i can see what mark responded to 0 deg or find the information anywhere? Even tried looking for a new timing tab on rockauto and summit and cant find one, do you know if there is a special tool or knack to getting onto the dizzy retaining nut as well? seems very well hidden and buried and ive already lost half an hour of my life trying to get a socket onto it

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        • #5
          Getting the fuel pressure to exactly 43 is not critical.

          Test tab for checking timing is a piece of tin that is welded to the timing cover. It has teeth on it for measureing timing. The balancer has grooves in the outer ring. The grooves are probably hard to see, but you can feel them, once you find one, put a little paint mark on it just to keep track.

          There are special distributor wrenches for accessing the distributor hold-down bolt. Any auto parts store should have them on the shelves, and they are double ended with diffrent sizes.

          As far as the other forum goes, it's a situation with ownership and management.
          -Brandon

          Race cars are like strippers. They only work when you throw money at them!

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          • #6
            thanks again, ill search for the wrench but they aren't common over in the uk, i didn't explain myself clearly, i can see the tab for the timing but i cant see any markings on the little pointers as they are all rusty so dony know which point on the tab is 0 deg? ive got the groove on the pulley marked but the timing tab attached to the block is the bit thats puzzling me?

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            • #7
              The pointer tab that is rusty will have a couple teeth on it, then a flat edge (on the right side) with a small tube coming up. The flat edge will be your Zero TDC mark.

              Remember you should check the timing with the tan wire disconnected. The tan wire controls the electronic timing advance. So when you disconnect it, the pointer should show true base timing (should be Zero degrees).

              Last edited by Aeroking; 04-19-2018, 06:50 AM.
              -Brandon

              Race cars are like strippers. They only work when you throw money at them!

              Comment


              • #8
                mate thats awesome thanks, i've ordered the wrench from rock auto to get sent over here as its not something we have in the uk and from that diagram my base timing is 4 deg out which explains a lot of the issues i have when i plug the turbotweeks chip in

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                • #9
                  Have you researched balancer ring slip? Your timing may be correct, but your balancer may have slipped.
                  -Brandon

                  Race cars are like strippers. They only work when you throw money at them!

                  Comment


                  • #10
                    i've not checked it yet I'm going off of turbotweeks information , i showed him some data of a run with his chip in and he suggested the base timing may be off (also mentioned balancer slip if i can't set it with a strobe). The engine is showing knock on the datalogger even at 0 psi boost but it also has a worrying rattle, I'm hoping that the timing is off a few degrees which could cause the rattle but knowing my luck it'll need the engine pulling and rebuilding. Ive got a new wideband to fit to it so ill try and correct the timing once my new spanner arrives then fit the chip again and monitor the afr, I'm aiming for a ten second truck eventually so ill probably have to pull the bottom anyway. Looking at the distributor hold down bolt with a camera its not the first time its been loosened or moved and with the stock chip the underbonnet temps are quote normal which i have been told is abnormal for these as they usually run very hot? With the new chip in i can barely touch either side of the hood after 20 mins as its so hot whereas with the stock setup the bonnet feels normal ambient temp. The truck came from Japan about ten years back and has at somepoint had a respray but there's no rust on it anywhere so I'm thinking it might have been smashed up at somepoint in its history but there is no sign of damage or repair

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