09/07/2008 This is excerpts from e-mails I have had with folks wanting to do boat EFI conversions. This may answer a few questions for you. PLEASE e-mail me if you want to discuss the boat setup. I'm putting this here as a reference, NOT as a way to minimize e-mails from people. THanks, David > Do you subscribe to DIY-EFI and GMECM discussion lists? We're always > discussing (cussing about?) different EFI conversions! see > http://www.diy-efi.org > I've separated your questions and answered below. Once again, feel free > to > ask more, I have converted 5 engines from carb to EFI so I have a fairly > good idea about what works and what does not! > > >>Did you have to reprogram the ECM? > It will work fine as-is, but some minor changes to the chip would be a > good > idea to turn off the sensors that that you don't have. As far as "real > time > tuning," "reprogramming the fuel and spark tables" or anything high-tech, > not required! Turning sensors on and off is simply checking or unchecking > check-boxes in the ECM configuration. You could make those changes on the > chip without altering anything else. It takes about 5 minutes. > >>What did you do with the extra wires in the harness? > I removed them at the ECM connectors so there are no extraneous wires > "taped > off" in the harness. The 2 round > connectors on the ECM box are C1 and C2. C1 goes to the engine TBI and > sensors; C2 goes to the boat harness and battery power, fuel pumps, and > diagnostic connector. > >>What vehicle has the ECM,s that you listed? > 1227747 - Most (if not all) TBI Chevy GMC pickups with V8 and 4.3V6; from > 1987 to 1995; most Astro Vans with 4.3V6 (most years) > 1226869 - Most (if not all) TBI passenger cars with Chevy TBI engines, > same > year range as above. This ECM is almost identical to the 7747 but has > anti-theft capabilities and cooling fan control. > >>How did you bypass the oxygen sensor? > It is an optional feature. Its only function is to maintain a > stoichiometric fuel air ratio for the proper function of a catalytic > converter. It really will not make any difference on a boat. It is > turned > off in the ECM calibration by un-checking 3 possible diagnostic codes, and > turning off closed-loop fuel control. > >>I did see where one kit has you drill and tap a oxygen senson under the >>exhaust manifold right where there is no water jacket. > I wouldn't drill the manifold in that location because it will only read > off one cylinder and that is no good way to measure overall fuel mixture. > If I needed to use a wideband on a boat to tune a really wild engine; I > would make a spacer and put it between the manifold and the turn-down > piece > where the water is injected into the exhaust. This spacer would only > have > a place for an o2 sensor and a flange on each end to bolt to the manifold > and to the turn-down piece. > >>Are the round connectors you mentioned like the military multi pin type? > Yes, they are a corrosion-resistant glass-filled polyester resin material, > but otherwise the same. Made by Deutsch IPD. > >>Does the ECM in the sealed bok generate any heat?Does it need a water >>proof >>vent? > It generates very, very little heat. No vent needed. > >>What year was the donor vehicle you used? > I beleive it was a 1986 Astro Van. > --- > .... as for the fuel pump, the high pressure pump is a "Master" brand > at Advance Auto Parts or Auto Zone. It's an external EFI pump for a Ford > Ranger, Part # E2000 in their Master line. It is rated from 0 to 90 PSI > so > it is well within its operating range at 15 PSI. You MUST place a screen > in > the inlet fitting. > The transfer pump is a standard carburetor-type low pressure fuel pump. > Master part # E8012S is an example which can produce 5 to 9 PSI. On my > system as a transfer pump it is running free-flow aside from the > fuel/water > separator in the inlet side. It is one of those clicking-solenoid type > pumps. > The high pressure pump from the van was in in-tank pump that has to be > submerged in fuel. It is not suitable for in-line use. There are safety > concerns with an in-tank pump in a boat due to the vented fuel tank (can > have air/vapor mix in the tank) and the fact that the tank is in the boat > with the occupants. Plus the tank in my boat is too shallow to fit the > pump. > Go to www.autozone.com and enter the part numbers above in the "search" > box for pictures and pricing. As for the cost of the rest of the system, > I > used stuff I had on hand mostly. The ECM housing and sealed connectors > would run around $125 if you bought all that new. > Find out which size engine your EFI system came from. If it is NOT a > 350, > you will need the injectors and EPROM chip for a 350 engine. The injector > size, physical engine size, and the settings in the EPROM must match or it > will run rich or lean. The EPROM can be updated with any calibration, but > it > requires use of a hard-UV eraser, and a chip programmer. The calibrations > can be obtained for free online at www.diy-efi.org . They have most of > them > there, especially for the very common Chevy applications. ----------------- >> ....I'm doing an efi swap too for my boat.. I was wondering what >> you did for the oxygen sensor (o2)? I'm thinking of putting it into the >> exh tube after the rubber boot to the exh manifold. Or could I run >> without one? any help would be appreciated- Chris >> > Chris, you really don't need one on a boat. The O2 sensor It is an > optional feature. Its only function is to maintain a stoichiometric fuel > air ratio for the proper function of a catalytic converter. It really > will > not make any difference on a boat. It is turned off in my boat ECM > calibration by un-checking 3 possible diagnostic codes, and turning off > closed-loop fuel control. > These ECM's use "speed-density fuel control." This uses a very accurate > pressure sensor (MAP sensor) monitoring the air pressure in the intake > manifold, and an engine speed signal (distributor pickup coil). It > calculates the amount of fuel needed based on these inputs, and on a table > that tells it the engine's "volumetric efficiency" at all possible speed > and > load conditions. In other words, it tweaks the result of the speed-density > calculation up or down depending on if the engine is in a strong or weak > location on the powerband. The O2 sensor only makes a small effect on the > fuelling to keep the catalytic converter cycling between slightly-rich and > slightly-lean, so it can both reduce NOx and oxidize CO and HC. Unless you > have a catalytic converter, it is really not worth the time.