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Broke Down.. Not getting fuel, Symptoms with FIX!

Discussion in 'FAST Support Forum' started by AaronMiller, Sep 13, 2017.

  1. AaronMiller

    AaronMiller New Member

    Joined:
    Mar 10, 2017
    I have had my Fast 2.0 running well (other than the famous COMM ERRORs from the handheld) for over 500 miles. I have been very happy with it! Last week I was out driving when the car run rough for about a 1/2 mile, and then quickly got progressively worse. It eventually stalled, I made it to a parking lot where I shut everything down and tried again. I could get the car started but only if I kept it well above idle (1200+ RPM). It was still running VERY rough. Eventually, after a few seconds, it would die again. I probably did this 4 times before it would not start at all. It got dark so we trailered the car home.

    The next few days I checked out the battery voltage (good!), ignition system (6AL, good!), fuel filter (good!), fuel system relay (good!). The only error I was getting on the handheld was MAP VOLTAGE. I called FAST and they told me to charge my battery.. I asked about the MAP VOLTAGE error but he seemed sure it was voltage. Seems like you spend alot more time waiting on hold than they do trying to find the solution to your problem. ANYWAY- I did some searching on this forum where a member had a similar issue and ended up replacing the MAP sensor in the front of the throttle body. I ordered the part from AMAZON for around $20 and installed it this morning. BAM- fired right up. I don't know if the torn boot on my original sensor was the culprit, but it was disappointing to find none the less. So, my reason for making this post is for anyone who has similar issues- this is something to look at.

    [​IMG]
     
  2. Fastmanefi

    Fastmanefi Active Member

    Joined:
    Jun 4, 2011
    Location:
    Sonora, CA
    This was a common failure due to the ethanol in the fuel when using a dual plane intake manifold. Long term fix is to relocate the map sensor off the throttle body connected with a hose with the nipple facing down so fuel cannot get to the sensor.
     
  3. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    This failure also indicates a fuel inversion problem and unequal cylinder fueling. If you have a dual plane intake, changing to a single plane design with a deeper plenum will be more beneficial - and at all RPMs. Changing from a dual plane to the single plane intake can often prevent MAP sensor failure in the TBI from happening again anytime soon.

    Like Fastmanefi said, the best solution for preventing a failed MAP is installing an earlier GM type MAP sensor on a hose per his directions. You just use the old failed sensor to block the TBI MAP port. FAST sells both the sensor and sensor adapter wiring for this fix.

    FAST 1-bar sensor FST-307007
    FAST wiring adapter FST-308031
     
    Last edited: Sep 13, 2017
  4. AaronMiller

    AaronMiller New Member

    Joined:
    Mar 10, 2017
    So, leave the current sensor in place, plug the wires into the adapter plug, but where do you mount the new 1-bar sensor? I have an Edelbrock Performer RPM Dual Plane intake but do not want to change that out for a single. If I change to the other style sensor and leave my dual plane- will it be better or is it the correct fix or is did I just have a MAP sensor go bad?
     
  5. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    You'll stop losing MAP sensors if you install the earlier model sensor and wiring adapter. You'll need to fabricate a bracket for the older style MAP somewhere near the TBI base plate. The adapter wires aren't very long.

    You will still have a far larger problem. The by far better solution is to get rid of the Performer RPM and get a single plane intake. With the single plane intake you'll dramatically increase low RPM torque as well as higher RPM torque and horsepower. Just one of the benefits helping this is you will be able to raise the initial timing, and set slope and advance, to optimum. Since you will be able to dial in a far better timing tune and A/F ratios, engine and manifold heat will go down, sparkplugs and wires will last longer, and the engine can idle better and lower. Emissions will also improve dramatically due to the much better tune a single plane intake allows with EFI.

    Your engine will be able to run better and cooler with any single plane intake using the 2.0 TBI - even the cheapest one you can find. The larger open plenum of a single plane dampens cylinder pulses for much improved TBI operation and provides more equal runner lengths for improved flow.

    The reasons why a dual plane intake is wrong for TBI (EFI):

    Dual Plane intakes were designed for use with carburetors to take advantage of the venturii effect fueling design of a carburetor by amplifying cylinder pulses along in-equal runners and using a divider. This allowed for better idle performance using a carburetor. The dual plane design amplifies fuel reversion in the intake and it is this that destroyed your TBI mounted MAP sensor in short order. EFI systems use timed electronic pulse modulation to control A/F mixtures - not venturii boosters. The dual plane venturii effect fuel reversion upsets the proper operation of EFI. The design of a dual plane intake promotes in-equal cylinder fueling. Fuel injection strategies rely on equal cylinder fueling promoted by the more equal runners in a single plane intake.

    Most everyone in this forum has seen, including FAST employees, the excessive problems caused by using a dual plane intake with TBI. Even when the problems aren't readily noticeable, they are there - and working against the life of your engine. The better tune allowed by using a single plane intake with EFI also improves cold and warm start.
     
    Last edited: Sep 14, 2017
  6. AaronMiller

    AaronMiller New Member

    Joined:
    Mar 10, 2017
    Thank you for the response. The engine is a Keith Craft built crate engine. They built it knowing I would be running the FAST 2.0 so I am surprised and disappointed to hear that this system does not respond well to the dual plane intake. I will have to call them to get their thoughts.
     
  7. fabr

    fabr Member

    Joined:
    Jan 23, 2017
    Since they put a dual plane on an engine destined to run EFI I doubt I'd really care what their thoughts are. Obviously, their thoughts are wrong.
     

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