• Changing Over to EFI

    by Clark Bird



    Board member Clark Bird (Griswald) takes us along on his journey to discover the basics of DIY electronic fuel injection modifications.


    I have often read posts on the various message boards from boaters who are either converting to EFI or going back to carburetors, for some odd reason. Certainly, EFI isnít anything new and has evolved with numerous companies providing hard parts as well as various software platforms that allow users to install and tune these systems themselves. Coming from a drag racing background, my tuning experience was all about carburetor jets, nitrous pills and reading spark plugs. This EFI stuff was brand new and a bit intimidating to say the least! However, I knew what made an engine run and how the different variables came into play to achieve horsepower. Iíd like to share some of my personal experiences with EFI and how Iíve taken the initiative to install and tune a Delphi Mefi4a on my 27í Fountain. It didnít happen overnight and there is a list of people to thank at the end of this article.

    A little about my setup: I purchased a í97 Fountain in 2007 with a ZZ502 crate motor, MPI and M1 Procharger. The ECM was an older model MEFI-1, which I later discovered was very limited in capability. The fuel system consisted of an SX electric fuel pump and the notoriously junky rising-rate fuel pressure regulator from Procharger. The boat ran pretty good that first summer but I lifted a ring land on #7 at seasonís end and knew it was time to freshen up. Dave Kropp at CHS Racing Engines had been building my drag motors for nearly 20 years and there was no other choice for me to rebuild this one. Once we got the motor torn down we found some cracked exhaust seats on both heads and upgraded to a pair of Dart Iron Eagle 308s. Besides a set of SRP flat top pistons and the very familiar Crane 731 hydraulic roller cam, the rest of the parts were stock including the MPI manifold and 42lb fuel injectors. I did, however, trash the Procharger regulator and went with a unit from Bell Engineering.

    When it came time to dyno the motor I contacted Full Throttle Marine in Spicewood, TX and owner Bob Lloyd. After the initial break in I remember watching Bob make adjustments to the timing and fuel tables. For the life of me, I could not grasp what was going on. I didnít even know enough to ask a stupid question. He would make changes while I just sat there with a dazed look on my face. BPW? What in the world is that? A couple dozen pulls later we ended up with approximately 550hp and felt that was a good place to stop and install back in the boat. I wasnít going for all-out power with this build so these numbers suited me just fine. I wanted to turn the key and go boating, not worry about engine reliability and Bravo parts scattered all over the lake. Bob Lloydís tune worked pretty well during the cooler temperatures of spring, but when summer time rolled around with the heat and humidity, the boat started running poorly and I found myself scrubbing soot off the transom more than I wanted to. My wife moaning about the fuel smell didnít help matters! So, what to do? I couldnít stand the thought of relying on others to dial this thing in (no offense to Bob Lloyd or anyone else) and figured it was time to get my feet wet and learn this strange and crazy, EFI. I had been reading about air/fuel meters and decided that would be the first step at trying to tune this thing myself. Reading more threads on the message boards gave me enough information to start some research and make a purchase. I bought a dual-sensor unit from F.A.S.T. and took my Stainless Marine risers back to CHS Racing Engines to have the bungs installed. Eddie Young, of Young Performance Marine, had made a couple posts describing how to do the job and thatís how I instructed CHS to weld them in. $150 later, I was ready to go tuning!



    The first runs I made showed the motor ran fairly efficient with AFR readings in the mid 12s, right where you would want a naturally aspirated motor to be. However, once I got into boost the meter would flat-line at 9.0 and the motor would not rev. Rich, rich, and more rich! Iíd stop, raise the hatch, make a couple turns of the needle valve on the fuel regulator and make another pass. This process was a bit cumbersome and no two passes were the same. Frustrated, and after some choice words, I was one of those wanting to go back to a carburetor. Ditching the Procharger was out of the question though so I took some time to think things over and realized EFI was the way to go. But, how do I go about this? The MEFI-1 worked fine but as I mentioned earlier, was limited in capability and unable to tune once in boost. Ultimately, I would have to upgrade the ECM to get where I wanted to be. After some thought, and shock at the prices some of these units command, I found Crate Engine Depot had a great deal on a MEFI-4a and harness for right at $600. WINNER! I would also have to find a way to tune the MEFI controller so I chose the MEFI Burn/Scanner/Tuner Pro setup. I had to upgrade to a 2 bar MAP sensor as well since I would be running boost.

    Once I received the ECM I could hardly wait to get it installed and hook up the software. The harness they sent was a bit tight so I had to do some cutting on the wire loom and stretch things out a bit. Being the impatient person I am, I ended up erasing the stock 502 Ram Jet tune that came in the Mefi4a. Luckily, Bob Radke, at OBD Diagnostics sent me a generic tune to get the motor fired. Once running, it wasnít pretty. It was spittiní, sputteriní and generally unhappy. Iím pretty savvy at computers and applications but didnít have the slightest idea where to look this time. On the phone to Bob at OBD again!



    Bob had me read a couple parameters from Scanner Pro as well as the AFR readings. Right away he suggested the motor was running lean and to go into the fuel tables and add some fuel. It turns out that Tuner Pro is a fairly easy program to use and it didnít take long to realize how minor changes to the fuel tables would affect the air fuel readings. A couple clicks here and there, upload the file and it was time to hit the water. Ideally, itís best to have someone with you to run the boat while you tinker with the laptop, but it can be done by yourself. I made several runs while recording data and would use my iPhone voice recorder to save the AFR readings at different rpm so I could take that information back to the house and make further adjustments. Itís worth mentioning that these changes can be made in the boat but time was usually a factor in my case and this process seemed to work best for me. I canít say I got the tune right on the first few tries and there have been many hiccups along the way.
    However, persistence paid off and Iím quite happy with the way the boat runs now. AFR readings are high 12s to 13.0 NA and 11.8 to 12 at full boost. The motor revs to potential and fuel economy has increased dramatically at cruise speeds. It starts, idles, goes in and out of gear without issue and has turned out to be quite a reliable package approaching 300hrs this summer. The next step will be setting up my AFR meter to record through the ECM and Scanner Pro. This will allow me to log AFR readings right to the laptop for further refinement. It never endsÖ Iím sure there are quite a few gear heads out there like myself, who may find themselves in this situation. Iím no expert, but I dove into this venture head first and can say that Iím glad I took the time, listened to the experts, and ended up with a great running boat and the satisfaction that I did it myself. For anyone that has some technical and mechanical ability, I say go for it!



    Dave Kropp Ė CHS Racing
    Engines Austin, TX
    Bob Lloyd Ė Full Throttle Marine
    Spicewood, TX
    Bob Radke Ė OBD Diagnostics
    Redondo Beach, CA
    Eddie Young Ė Young Performance Marine
    Mount Juliet, TN
    Jim Speros Ė Mobile MercMan
    Jonestown, TX


    Clark BirdÖ