Swap to TBI

"I just picked up a TBI setup

"I just picked up a TBI setup from an 87 chev 350, and was wondering if its worth it to install it on my carb'd 86 Four Winns with a 350 chev. Or, should I just rebuild the carb? I'm removing the intake to clean it up anyway, so it's the prime time to do a swap if it's going to be a better setup."

"Mike,

Would love to hear h

"Mike,

Would love to hear how this comes out if you make the change. Would certainly be a small challenge. In thinking this through, my opinion from a car guy theoretical perspective is that you are likely to have two issues.

Calibration:
I've gotta believe the TBI set up may take some effort to run correctly on the boat... despite having adaptive learn capability. Cam, heads and operating temp are different and therefore so would be the volumetric efficiency that the TBI system is set up for (assume you would use the truck intake manifold). Means the PCM would need recalibration. Think those years had replaceable prom chips so reprogramming would be feasible. Who knows. Might run fine.

Physical conversion:
Your boat motor would need to have a location to put various sensors that provide input to the TBI "speed density" fuel injection... such as crank sensor and O2 sensor (new manifolds?). MAP sensor, temp and TPS as well as IAC would all be on the "new" manifold and shouldn't be a problem. You would need to use the truck distributor et al, as the PCM controls the ignition curve. You would need a fuel line returning to the tank. You would need to make yourself a harness (no butt connectors).

Some of the more experienced boat guys may have seen this conversion... I haven't."

so what if I just dumped in th

so what if I just dumped in the whole motor from the truck I'm pulling it from?

"The MAP sensor uses the hose

"The MAP sensor uses the hose from the bottom of the throttle body mounting plate, the TPS and IAC are on the throttle body already. The knock sensor goes in the hole on the block for the petcock, the TBI motors don't use a crank sensor, they use the distributor with the IC module built in (look at a late '80s - mid-'90s pickup). For the harness, I would use heat-n-seal connectors if I wanted to make it match the boat harness."

"Edited,.....

With some of

"Edited,.....

With some of the advice I see here,.......

There's going to be some Serious Explosions......"

"Bondo- What will cause an exp

"Bondo- What will cause an explosion, based on the info given here? Care to elaborate? It would be a lot easier to just rebuild the carb but as long as everything is done correctly, it shouldn't be a problem.

The marine motors with TBI use off-the shelf throttle bodies, sensors, distributor and as long as the starter doesn't shoot sparks, that won't cause any problems. The fuel pump is the only issue because it needs to send 18-30 lb of pressure and the regulator can return unused fuel to the tank. As a matter of fact, the original TBI boat motors didn't even have a return line, they had a bypass at the pump.

I'm not sure I would do a conversion like this without having access to people who are fully qualified and able to acquire the diagnostics and do a correct calibration. I wouldn't use a car/truck ECM- it's not made for the marine environment and in that, I agree with Bondo. The car ECM is only somewhat adaptive. If things are way off, it'll throw codes and run like a stove. Marine calibrations are not available for cars and trucks- the only way it may match is by coincidence. The operating temp is easy to change- getting the calibration/fuel tables right isn't.

If someone has access to people who are able to do the recal, it might be OK. If not and the original ECM is used, it's gonna be really frustrating and potentially dangerous to the motor and by extension, the passengers."

"I'm Sorry Jim,....

The

"I'm Sorry Jim,....

These Automotive Fuel Injection conversions are Basically a No-No to the average Joe on the street.....

Playing with Gasoline on a Boat is Bad Enough,...
With this we have High Pressure Gasoline.....

Maybe I'm underestimating the the general mechanical knowledge of most of the posters found on, not only this board, but All forums.....

Your posts about this seem to me, lead to this being a Cakewalk thing to do,...
While I'm Sure that You could pull this off,.... I don't think it's within the grasp of someone who just wants to Dump in the Whole motor,+ expect it to Work.......

Just as you go More into Detail in your reply to Me,... In your other posts,..You left out All the details of doing this task Safely,.. If that's even Possible.....

I post Alot on Alot of boards,....
Most people want to know Which Part # bolts to what... If they can't just go out,+ Buy that ECM,... It Ain't gonna Happen....

Your 3rd paragragh alone sums up why I keep telling folks that it's Not Really a Doable Swap.....

And,.... In All of this,... No Mention of a Fuel Pump Cut-Off Switch,.......
I try to think of peoples Safety,....
As well as How to Fix their Boat........"

"Part of the reason I would ne

"Part of the reason I would never tell anyone how to do the whole job is that they're going to blame me if they mess it up and I should have stated that in the beginning. Is it possible to do the conversion? Sure. Is it easy, NO. You'd be surprised how easy it is to buy the right ECM for this. The hard part is getting the right program.

You're probably right about making it sound easy. It's not really incredibly hard to do if the steps are all done correctly and all of the safety measures are taken. I did leave out a lot of what is needed to do this job but,again, I don't want someone trying it and coming after me and I surely don't want to hear that someone followed instructions I had posted and was injured or killed. If someone paid me to do this job, that's one thing but just asking in an online forum shouldn't make anyone think they have all of the necessary information for something like this.

FOR ANYONE NEW WHO READS ONLY THE MOST RECENT POSTS, SINCE I CAN'T EDIT MY PREVIOUS POSTS BY ADDING SAFETY PRECAUTIONS, I WANT TO SAY THAT I'M NOT RECOMMENDING THAT ANYONE TRY THIS CONVERSION. WITHOUT KNOWING EXACTLY WHAT IT REQUIRES, IN PARTS & TOOLS, SKILL AND KNOWLEDGE, IT COULD BE EXTREMELY DANGEROUS!!!!!!!!

In the TBI/MFI systems on boats, if the motor quits, the pump stops automatically. I could post a diagram but I won't."

"The coast guard has some regu

"The coast guard has some regulations concerning fuel systems on boats. Go to their website and see what they require boat builders to do to get the coast guard's thumb's up.
Here's a for instance:
Electric fuel pumps are required to be the "two diaphragm" type. What this means exactly I'm not sure, but the reason behind it is so that a single failure doesn't result in fuel in the bildge. Does the TBI fuel pump designed for cars meet this standard? I honestly don't know, but it's an example of the safety type concerns you have to answer along with the other questions.
BTW there are more components beside the starter that are marine specific... distributor, alternator to name a couple. Mounting the O2 sensor continues to be an unaswered question... you could do a straight through exhaust, then you have to figure out how to get the raw water out of the boat."

"Many of the electric fuel pum

"Many of the electric fuel pumps used have an impeller, not diaphragms and the one Indmar has used from '93 until '98 on Mastercraft boats was a Chrysler part. Since '98, MC has had the pump in the tank and that's a Carter automotive part. The CG was very skeptical about making sure the lines were durable enough and that there were enough safety measures in place. AFAIK, there have been no line failures or leaks at the fittings. The distributor is a generic car/truck part and is sealed. The alternator is easy enough to deal with. O2 sensors haven't been mandated until recently and '07 is the first model year that has them in boats. When I was at Mastercraft training in late '99, the development team had been testing different methods of mounting that sensor that would work in this application. They are also using a catalytic convertor now and they have developed the current system based on C.A.R.B. and the EPA emission specs.

The raw water can go out the exhaust, just like normal on a lot of marine motors or there are ways of having a dry exhaust- I would lean toward the normal way (PCM, Indmar and Mercruiser have done it this way in ski boats for years and the manifolds are easily obtained) or in a dry exhaust system."

"So, if you have an automotive

"So, if you have an automotive system that has an O2 sensor and you want to take that system and put it on a boat engine, what do you do with the sensor?

How does that affect the system?"

"The car ECM will probably hav

"The car ECM will probably have issues with the lack of an O2 sensor and will go into its default mode. The fuel delivery won't be right and if it's too rich, it can dilute the oil, not to mention the other issues that can come up. An O2 sensor won't live if it gets wet and with a wet exhaust system, that's a problem.

Come to think of it, the car TBI injectors may not work- the boats have truck injectors.

Again, the car program for the ECM will not work on a boat- the fuel table is too lean and the motor won't last long. As I said before, unless the knowledge, parts, tools, skills, and testing are in place for this kind of job, I wouldn't do it. Other than the parts installation, it's not a weekend project. The system needs to be complete or there will be problems."

""just asking in an online

""just asking in an online forum shouldn't make anyone think they have all of the necessary information for something like this."

Unfortunately,...... That's what Does Happen.....

Just as an example, I happen to be an advocate of Dry winter storage,... Rather than dumping Anti-Freeze into the motor,+ then into the lake.....

There's a fella over at iboats whom I explained the process to,....Along with the "Gotchas" that go along with it,......
The following spring, last spring to be exact,.... He posts that his engine was Frozen,+ Busted the Block,.....
And,...... It's My(Bondo's) Fault,......
Upon further questioning,... He admits that he Just pulled the drains,+ DIDN'T rod them out with a nail, or screw..... He said that Plenty of water exited the block,.... Obviously, that's Not the Case......
Sooo,.... Now he's posting around the web with a slogan Very similar to mine, which at every board but this 1 is,...."Any Grease is Better than No Grease at All".....
Only in his, it's Antifreeze instead of Grease....
Now I'm the No Good Sumb!tch,.......'cause He couldn't follow directions.......

Jim,.... Again I'm sorry for calling you out on this,.... But I don't think you give yourself enough credit,.....
Many people not only look up to the knowledgeable posters on these forums,....(which you Are 1)
Some people take Our Word as Gospel Truth.....

I Respect your Words,+ can See that you are Very Knowledgeable in these matters,......

Again,...... No disrespect intended......."

"No problem, I should have lai

"No problem, I should have laid out the good/bad of a job like this in my first post."

...as should I. Think some of

...as should I. Think some of us dwell on the interesting problem solving aspects of the topic and don't always shine enough light on safety and direct guidance for those who may not have advanced skill sets. "go with the carb rebuild" should have been my first advice. Hays

"With all the advice I've

"With all the advice I've gotten here.."go with the carb rebuild" is the best I've seen. Gonna leave it as it was made, and enjoy what I have...safely. Thank you all!!!"