Carb vs EFI ?

[skialot2]

It was 60+ today so I tried the boat out. Still no good. It's better than it was. I got it to plane off. But still has no power. I am stumped! I don't know what else to check. Besides being down on power, the motor runs perfect. It starts with a click. Runs very quiet. No noises coming from the block. It doesn't misfire. It doesn't shake. Idols in and out of the canal smoothly. Never stalls. Just has no power. It's driving me nuts. The only thing I can think of trying is to take the entire induction system off my carb engine and put it on the EFI block. If it runs good with the carbs, I know there is still something wrong with the EFI system. But if it still has no power, I know there is something wrong internally.

[LakeFever]

Your 100% certain the throttle bodies are opening 100% yes?

[mercrazy]

Are timing advance wires hanging up? Old wires get stiff. I’ve seen the wire retainer too tight. Push throttle with control box or hotfoot, not pushing the throttle arm by hand and see if it’s hitting stop.

[rjdubiel]

Not sure this will help you but I would put money on it. Get a Brucato and try it, anyone by you have one for a PM you could try?

[skialot2]

I don't know anybody with a Brucato. But I have an A30 and two A8's. They all run the same. At least before cleaning the injectors.

I already changed the entire ignition system. Converted it from CDM to switchboxes. Timing wires are fine. I am getting full advance when I manually push the throttle with the cable disconnected. I am going to have to check the Hotfoot stop tomorrow. I never checked it after the last link and sync. And I did a lot of adjusting on the linkage to get it to idol timing set. I hope that is all it is.

[LakeFever]

I don't know anybody with a Brucato. But I have an A30 and two A8's. They all run the same. At least before cleaning the injectors.

I already changed the entire ignition system. Converted it from CDM to switchboxes. Timing wires are fine. I am getting full advance when I manually push the throttle with the cable disconnected. I am going to have to check the Hotfoot stop tomorrow. I never checked it after the last link and sync. And I did a lot of adjusting on the linkage to get it to idol timing set. I hope that is all it is.

there’s a cam arm on the throttle linkage that only opens them all up after 50% or so of throttle. I did notice when setting mine up this whole deal was pretty sensitive and I messed with it a while to get it where full throttle was opening them all up fully without taxing the linkage, or not opening fully. Taxing meaning the blades were fully open but the cable had more to move so the pressure on the pedal was taxing the linkage so to speak. Figured this would lead to breakages or worn prematurely worn parts.

Don’t ask me about the first dbw gen 4 ls swap I did that stumped me for a month with low power lol

[rjdubiel]

I have had issues with all the PM stuff that needs to work together with the merc ecu. Brucato pass all that and just runs off RPM and vacuum, if you had one close to try quick it would be completely worth it.

[LakeFever]

You’re also going to need to set the TPS if you haven’t don’t that yet. There is an adapter harness available from buckshot that works great or you can use some tiny wires to slip in between the connector

[skialot2]

Yup!!! Hotfoot is the problem now. Looks like it only opens the throttle about halfway. I am surprised I was able to get it too plane off. Now the problem I have is it takes the full throw of the throttle cable to go from idol to full throttle. if I adjust everything so I get full throttle, I don't have enough spring pressure on the Hotfoot to return to full idol. I think there is too much play in my throttle cable.



throttle play

[skialot2]

You’re also going to need to set the TPS if you haven’t don’t that yet. There is an adapter harness available from buckshot that works great or you can use some tiny wires to slip in between the connector

Thanks. After I got this motor, the first thing I bought was the TPS test harness. It was set way off, but it wasn't the problem.

[mercrazy]

Might be a bad cable or need a new or bigger spring. See where the spring is mounted. Some hotfoots have multiple locations to mount it. Also some hotfoots have more than one place to attach cable.

[skialot2]

The hotfoot is now operating the cable through its full range of travel. The spring on the hotfoot is pulling the pedal back to its idol stop. But the cable is not pushing the linkage back to the idol stop on the motor. It's a cheap no name cablet that seems to have a lot of play. I am going to get a set of quality cables and see what happens.

[skialot2]

I checked a bunch of other cables I have, all the wrong lengths of course. They all have about the same amount of play. So I put an old school throttle return "spring" behind the throttle arm. It doesn't really belong on my motor. The casting for it is still on the throttle arm. But the hole is not drilled for it. I had to drill the hole for the spring in the throttle arm and in the block. I have a 1986 135 that has the spring in it. So I pulled that throttle arm to measure where to drill the hole in the block. Now the throttle arm returns to idol all by itself. Even without the hotfoot connected.

[skialot2]

It was 80 degrees out today, so I went for a quick test ride. It's all fixed. Runs great. Nice and smooth. As soon as I went out the temperature went from low 80's to high 40's in like less than a half hour. So, I wasn't out long. But I think my carb motor might have a little more power than this one. That makes sense. This one is completely stock. The carb motor is just rebuilt with some bolt on performance mods. Boyeson reeds, Bobs tuner and exhaust housing. No can. So, it should be faster. Now that this is fixed. I think I am going to take it apart and rebuild it. Do some porting on it. New rings, Metal cage rod bearings. Upgraded rod bolts. Plus, all the bolt on stuff. Maybe get a ProMax ECU or even a Brucato. This motor runs good now. But it definitely was not maintained properly. It's never been apart. The Powdercoat is still sealed on the block halves, the heads and head bolts. Even the thermostat housings are still sealed to the heads. 20+ years on the original thermostats. They still seem to work fine.

[LakeFever]

Glad to hear it was not something expensive to remedy. Bumping compression is the biggest gain and yes RPM limiter is the issue that keeps a stock motor from really winding up. I managed about 6300 with my A8 box. It did get great fuel mileage with that box at part throttle. Wide open it’s not good because they enrichen to limit rpm. I added the 225 promax box but it’s way too fat for a 4/5 pedal low compression motor. A 200 promax box would be a nice gain if the price is right. A brucato is the best path. I’d get the unlimited box and use fuel pressure to dial it in. I’m building a new power head and then it’s probably the unlimited brucato mod next. I like to take things in stages. Helps me understand exactly what the motor is doing and what it likes