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2004 TLDI MD90, unable to pull any codes/engine hours and no beep when turning key, cranks up fine

D

defrag4

Member
Hi guys,

Recently bought a used 2004 TLDI MD90 from a friend, he said everything was running well on his boat when he pulled it a few months ago. I got the controls, wiring and gauges from him as well.

Got it installed on my boat yesterday and took it out for a sea trial today. She fires up instantly and idles fine, an occasional slight rpm surge, but she is running LOUD (maybe normal?) and vibrating alot, pissing water just fine and not overheating but with the noise/vibration I was worried to get too far from the marina

I stuck her back on the trailer and came home to do some more research.

I am trying to check the codes or pull the engine hours via pushing the key in on the ON position for 5 seconds, but it is not doing anything. When I first turn the key to ON, all 3 of the dummy lights do light up and turn off in a second or 2 as expected.

I also noticed I am not getting any chime when I turn the key to on.

The person who installed the motor was not very familiar with TLDIs so not sure if he possibly hooked something up incorrectly to the tach? the tach did work and show RPMs while in the water

Any ideas on why I would not be able to pull the codes, or at least check the engine hours? Also why no chime on key turn?
 
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I am down in Baja, MX, Tohatsu is not distributed here so not many people mechanics familiar with this motor, hopefully I can figure it out on my own.
 
[FONT=&quot]hmmm I am reading about both the battery and throttle position being issues, both of which have changed since we moved the motor to a new boat, I tracked down the MD90 service manual[/FONT]
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[FONT=&quot]tomorrow I will buy a new battery and do the throttle cable adjustment procedure to get her dialed in, I will also double check the grounds

Still not sure why that would lock me out the diag mode and eliminate the ON buzzer, so perhaps not related[/FONT]
 
Alrighty, went out and got a brand new batt with 950cca, my buddies was only like 600 and 1/2 dead

still having issues she’s running rough and idling poorly, if I try to give her gas she will rev up and then die

kind of seems like something related to the TPS

i also discovered a wire had pulled out of the back of the Tach remote control harness which explains why I wasn’t getting any codes or feedback from the motor at the start switch, also found my buzzer wire was cut.. fixed both those issues, now I have the buzzer and am able to pull codes, there were none stored, ran the motor for a while, still not throwing any codes, if I pull the TPS when she is running it will throw a code so I know that’s working

Also learned she has about 600 hours on her according to the tach

i am looking over all the wiring now, wiring looks fine at the motor but the wiring up at the controls is a bit suspect

I recorded a video of her running, and me changing gears around, then back to neutral, u Can hear how erratic and loud she is

https://youtu.be/OAv8pahT_KM
 
Well I removed and cleaned up all the grounds i could find under the cover, and cleaned up some of the wiring under the dash

Still idling all over the place and dying when I rev her up :-/

Back at it tomorrow, my mechanic is convinced is mechanical like bearings, but I’m pretty sure it’s electrical, fuel/air sender related
 
defrag4 said:
Well I removed and cleaned up all the grounds i could find under the cover, and cleaned up some of the wiring under the dash

Still idling all over the place and dying when I rev her up :-/

Back at it tomorrow, my mechanic is convinced is mechanical like bearings, but I’m pretty sure it’s electrical, fuel/air sender related
Click to expand...
Doubtful a bearing issue. What are your fuel and air rail pressures? Are you running DFI oil?
 
thanks for the reply paul!

Will check on the pressure tomorrow, I am running whatever oil was in it already when I got it, i assume its DFI, probably wont hurt to drain it and refill with known DFI oil

everyone knows what happens when you assume the previous owner knew wtf he was doing
 
Got back out there today, found a mechanic in town who had both styles of fuel/air pressure gauges (basically AC gauges) and we pulled the fuel pressure, looked good, pulled the air pressure and it was super low ~30psi, hmmm

removed the air filter, still no pressure

Mechanic said he had worked on Optimax in the past and had seen the gaskets in the air compressor fail, so he started tearing into it, ended up breaking off 2 of the rusted bolts in the pump, bit of drilling and ez-outs later we eventually got it apart down to the piston inside the compressor

Gr8zRxc.jpg


found the piston to be very loose in the cylinder, lots of side to side play, not sure if its the cylinder walls, rings, or the piston itself but something seems screwed up and explains why she is not making any air pressure

https://youtu.be/L1ntJ08oVUE

After a bit of hemming and hawing with the mechanic on what we could do I recalled reading a post by @pvanv that mentioned you could bring in outside air and pump it into the motor, as long is it was within the proper psi specs it should work

So mechanic went to his house and brought over a pancake compressor with variable pressure, we wound it up to around 90psi and cranked her up, she ran great for a few seconds and then started to die as the psi dropped off in the small compressor... hmm we need a bigger tank!

luckily i know a guy in town with just the tool... called up our mobile tire repair guy and he drove on over

HerGyWV.png


he thought it bit a weird when I told him what the hell we were trying to do, but he was game

Unfortunately his compressor was dialed in at 220psi and the knob had long rusted shut, so i had him cut off the compressor motor and i just drained the air from the tank by holding down the nozzle valve, eventually got it down to ~90psi, jammed the spray nozzle down the air hose on the motor and had a buddy crank her up

ran like a friggin top!!

I had him rev it all up and down, all over the place, she finally sounded like a real motor!

problem located!! lots of celebrating all around as at this point pretty much everyone in the town knows about me trying to fix this motor


now... how the hell to replace/fix this Tohatsu air compressor in the middle of nowhere Mexico...

the saga continues but I am just glad to have finally pinpointed the problem
 

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doing some further reading im wondering if maybe the reed valve in the air compressor is the culprit, or perhaps the rings

i will go pull it off the boat tomorrow and take a closer look

either way i am buying some new rings, gaskets, and bolts for the air compressor as the mechanic tore them all up on removal

i do not see any used compressors on ebay, new one looks to be about $700, so I am hoping I can rebuild this one
 
Piston, rings, and rod is available as an assembly for under $100. Ditto for the reed if it tests bad.
 
Thanks pvanv, i was looking online at the parts last night, seems like a much better deal than a whole new pump

i am trying a Hail Mary first and driving down to the next town where there is a shop that rebuilds agricultural pumps, maybeeeee they will have something for me there, but more than likely will order the piston and rings from the states

any idea how I can test out this reed valve? It looks ok to me aside from a bit of salt buildup but I’m no expert
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Well, those valves clearly are not sealing.
BTW, the fuel pressure is regulated about 10 PSI above the air pressure, so if the air was low, so was the fuel.
 
Thanks Paul, i found a local mechanic who was able to rebuild the piston and rings, got it back together today and the pump is still only making about 40psi at idle, and 50psi at revs, runs like crap and dies when we give her juice

i am guessing it has to be that valve as it’s the only piece remaining, looks like I am ordering one from the states, wondering if I should go ahead and just order a whole new cylinder, piston rings and valve just to cover all my bases, not sure how much more money I want to throw at this thing before I try and bring it back to my buddy...

i feel like I’m so close!
 
Today when I was checking the air pressure, i noticed a small amount of fuel that seemed to be coming out of the air side as well? It was a mist mixed with air, but certainly was gas
 
welp... crappy mexi hail mary air compressor piston rebuild job seized up on me today while doing further testing...

now we wait on a replacement compressor from the states :*(

Is there anyway to test that fuel regulator without starting the motor? Will it build pressure just off the FFP running with key in ON position? I did not see any tests in the manual for it outside of the 90psi check when engine is running

I am still slightly concerned about finding a bit of fuel in the air schrader valve, not sure what that was all about, though I am 99% sure our problem is the air compressor

I really appreciate your help Paul!
 
If the compressor seized, was there oil running to it as it should?
If you have shop air, yes, the regulator should elevate the fuel rail 10 psi above that.
 
welp I got an entire new to me (ebay used) compressor on there and still have the same problem, I had my buddy with the truck with big air compressor come back over and if we shoot air straight into the hose where the air compressor is going into the air rail, bypassing the compressor, she fires right up and runs great

So either this used compressor is junk as well... or something else crazy going on, any other reason that the compressor wouldnt put out enough air?

the belt looks fine, flywheel looks fine, pulled the air filter off as well to check, no issues there

If I crank the motor to start up with my air pressure gauge attached i can see it only builds about ~30psi and wont fire up, if I give it about 1/2 throttle I can get her to fire up, she revs up to 4000 but she dies if I try to bring the RPMs down below ~2.5K, I assume because the air pump isnt putting out enough psi to keep it running

I pulled the oil send and return lines to the pump and can see oil flowing there, so i assume its ok
 
I am starting to wonder if there is some sort of issue with the air regulator, maybe the shop air (120psi) is strong enough to overcome it and the onboard air compressor is not?

Is there any way to test the regulator?
 
alrighty... back at it today

I rigged up a air pressure gauge with a NPT fitting that I could thread directly into the air compressor to test if it was putting out the proper PSI, heres a video! it take a while but it does build up to 80-100psi, so I am thinking it is OK?

https://www.youtube.com/watch?v=pSJWHQdMJoM&feature=youtu.be


I went up to autozone and rented a proper fuel pressure gauge so i stop ruining my air gauges...

looks like were only getting 65psi of fuel, and 75 psi of air, should be reversed shouldnt it?

bad fuel regulator? bad fuel pump? Something else?

I noticed fuel in the air line coming out of the bottom of the airpump, dont think there is supposed to be fuel in the air compressor? any idea how that could have happened?
 
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also discovered that I had a leaking schrader valve at the air rail side, I fixed that and now I can fire her right up without having to give it 3/4 throttle, still have low fuel/air pressure, but ill take a small win lol

still running like crap and loud as hell, but at least shes running!
 
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