Help on Mercruiser TBI or MPI Injection Upgrade!

[bvprice]

Here goes my first post! I have a 1986 Crestliner 25' Cuddy, with a Merc. 260 H.P. Chevy 350 I/O with a Gen II outdrive (Low hours on the whole outfit!!). I am cosidering upgrading from the stock 4 bbl carb., to a TBI (Throttle Body Injection) or a MPI (Multi-Port Injection) fuel delivery system. I am planning on robbing the system( along with the ECM) from a wrecked vehicle. This may sound odd, but I want to keep my boat and improve upon the exhisting Carbed system. The headache of the carb., not to mention performance gains, are my main reasons for wanting to perform this swap. Has anyone heard of or have yourself performed this modification? I am aware of some of the actual mods that need to be made (for MPI...my first choice). I know that I will need to install a high-output electric fuel pump with return as well as an oxygen sensor (I also thought I might be able to use a closed loop system). An upgrade in the distibutor is necessary to allow the computer to advance or retard the timing. I was planning on getting this from the donor vehicle. The wiring for the ECM would be relatively simple... positive, negative, O2 sensor, fuel pump and distributor. To my knowledge, pre '97 (non-vortec)Chevy heads and blocks are all the same, and I assumed this would apply to marine engines as well. The TBI option is not my first choice, but any input on it , too, would be appreciated. Does anyone with a newer boat have MPI or TBI on it?

 

[Don S]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

You need a MARINE system, not automotive. Forget automotive fuel and electrical systems on boat.

 

[bvprice]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Is there a reason for this? I was thinking if you kept it watertight (the ECM), what could be the harm? Unless I'm upside down in the lake, water shouldn't be an issue. I'm landlocked in Wyoming. No 8 ft. ocean swells to deal with here!!!!

 

[bvprice]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

What would you suggest then? Can you get marine upgrades for this type of application? Any other input would be helpful.

 

[Don S]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Parts for the electrical and fuel systems must be US Coast Guard approved for use in a boat.<br />I haven't messed with any of the aftermarket types personally, but have "Heard" (no experience) good things about the Holley systems.<br /><br /> Holley marine

 

[rabidfish]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Not to mention the automotive system will not run right. THe ECM will find all manner of "missing" and "out of range" sensors, setting codes that don't even exsist on a marine system...

 

[rabidfish]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Mercruiser makes a replacement engine with EFI.<br />ready to run, right from the crate...

 

[snapperbait]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Here's another option, Titan.. http://www.turbocity.com/default.php?cPath=16_22

 

[waterone1@aol.com]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Welcome to Iboats ! I have to say "ditto" on the above advice. Besides a serious safety issue with the auto parts, the calibration for everything will be way off ! A car ecm will be waiting forever for that engine to get up to operating temp....which it never will as the boat should be running 140 degrees (raw water cooled), and 160 (heat exchanger) while a car should be over 190. The spark advance and several other things would be off as well. Something in your post had me curious, did you replace the drive with a newer one ? You said it was a 1986, but said it was a genII drive ?

 

[Bondo]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Here's another option, Titan.. http://www.turbocity.com/default.php?cPath=16_22 <br />

Even thou this system Says Marine,......<br />I'd like to know Where you're supposed to mount that O2 sensor in a Wet Manifold, even if it Did come With the adapter.........

 

[Dunaruna]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Boomyal researched this topic a while back. The 02 issue was also raised. <br /><br />If my memory serves correctly, a manifold was under development so that a sensor could be incorporated to allow a closed loop system.<br /><br />Aldo

 

[Reel Poor]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Seems like I remember reading in my Volvo electrical manuel [2000 year model] you could install an o2 sensor in the top of the exhaust riser for testing purposes. They are made of stainless and wouldnt get washed down with water there.

 

[bvprice]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Originally posted by waterone1:<br /> Welcome to Iboats ! I have to say "ditto" on the above advice. Besides a serious safety issue with the auto parts, the calibration for everything will be way off ! A car ecm will be waiting forever for that engine to get up to operating temp....which it never will as the boat should be running 140 degrees (raw water cooled), and 160 (heat exchanger) while a car should be over 190. The spark advance and several other things would be off as well. Something in your post had me curious, did you replace the drive with a newer one ? You said it was a 1986, but said it was a genII drive ?

Sorry, my bad...It's not a gen II, thinking it's an Alpha or Bravo. I can't remember now...I've only had the boat for a year and it's in winter storage. I'll have to check later. Here's something that concerns me. My boat has NEVER ran at 140 degrees. Running temp is average 160-190 and at idle on a hot day it sometimes goes to 240. Is this a problem? You have me worried now. Keep in mind it stays cooler running at over 20 mph.

 

[tommays]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

thats way to hot how old is your raw water pump <br /><br />if your raw water cooled you should be below 160 max and if you have a heat exchanger FWC 180 max <br /><br />tommays

 

[Bondo]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

You said it was a 1986, but said it was a genII drive ? <br />Sorry, my bad...It's not a gen II, thinking it's an Alpha or Bravo. I can't remember now...

There Was No Bravo in 1986......<br />You've got an Alpha 1..........<br /><br />I'd Also say that you have a Very Serious Over-Heating Issue..............<br />

temp is average 160-190 and at idle on a hot day it sometimes goes to 240. Is this a problem?

I Don't Know, Maybe it's Just Me,.......Personally, No matter What Seat I'm sitting in, When I see 220*,........<br />I've AlReady Stopped to See What's Up ..................

 

[jstcrzyengh]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

I know as a matter of fact that the Turbo city setup is only a marine pump, not a marine setup. It is the same setup that can be had on ebay from a late 80's Camaro for $300 for intake to ECM. I believe you can remove the 02 sensor, you just need to find a place to run the IAT sensor. I looked into the TBI setup, but I dont think there is an accurate way to run it...

 

[waterone1@aol.com]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Sounds like it is time to stop all thoughts of changing fuel intake and get down to the real business.....why is your engine running so hot ?<br />If you don't know the history of this boat, I would suggest that you start by changing the raw water pump in the outdrive and the engine thermostat. One or both of those should take care of your problem, if not, time to start some troubleshooting.

 

[bvprice]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Originally posted by jstcrzyengh:<br /> I know as a matter of fact that the Turbo city setup is only a marine pump, not a marine setup. It is the same setup that can be had on ebay from a late 80's Camaro for $300 for intake to ECM. I believe you can remove the 02 sensor, you just need to find a place to run the IAT sensor. I looked into the TBI setup, but I dont think there is an accurate way to run it...

I agree! I was thinking the same thing! What is the difference? Nothing, except $300 used off a car and $1300 to $1600 for "marine" application. A matter of fact one of the kits didn't come with the ECM. It said to use a "compatible" computer. My guess, one from a wrecked car.

 

[bvprice]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Originally posted by waterone1:<br /> Sounds like it is time to stop all thoughts of changing fuel intake and get down to the real business.....why is your engine running so hot ?<br />If you don't know the history of this boat, I would suggest that you start by changing the raw water pump in the outdrive and the engine thermostat. One or both of those should take care of your problem, if not, time to start some troubleshooting.

I assume the "raw water pump" is the little rubber impeller inside the outdrive. Does the thermostat have to be "marine", or can I pick one up at a parts store? What temp should I go with?

 

[Boatist]

Re: Help on Mercruiser TBI or MPI Injection Upgrade!

Since water boils at 212 degrees you do not have any water in your engine at 240 only a little steam. Steam will not cool your engine at all. Even nascar engines only make about 20 laps when the water tempature hits 250 degrees. Many try and make it to next caution and about half bring out the caution from oil pan failure.<br /><br />Since marine engines are not pressureized and do not run antifreeze water does start to boil at 212 degrees and turns to steam.<br /><br />Do you ever start your motor with the out drive not in the water??<br /><br />Most engines run a thermostat in the 140 to 150 degree range. If it only over heats at low speed I dout it is the thermostat. Yes the rubber impeller could have all the ends worn off and not pump any water at low speed. Also possible to have a leak in the outdrive pivot area that allows all the water to leak out at low speed.<br /><br />If you have not already damaged your engine beyond repair you need to fix it before you use it.