PDA

View Full Version : Temp sending unit voltage


turbozinke
04-09-2012, 10:51 AM
My boat is not running well 2000 Mastercraft 205V with a 2006 indmar engine. I pulled of the wire to the temp sending unit from the ECM and it only has 5V. Same with the oil pressure wire. I also only have 5V at the gauges (oil pressure, temperature, and fuel level don't work) How many volts should it have? I assume 12V

Thanks

JimN
04-09-2012, 11:16 AM
My boat is not running well 2000 Mastercraft 205V with a 2006 indmar engine. I pulled of the wire to the temp sending unit from the ECM and it only has 5V. Same with the oil pressure wire. I also only have 5V at the gauges (oil pressure, temperature, and fuel level don't work) How many volts should it have? I assume 12V

Thanks

How many wires to the temperature sensor- one, or two? If it only has one, you need to check the sensor with one yellow and one black wire if you want the one that reports to the ECM. However, the temperature sender only sees 5V from the ECM- it's the return voltage seen by the ECM that matters, from all sensors other than the knock sensor- (ECT, TPS, MAP) and the knock sensor basically acts like a microphone, picking up vibration from knock in specific frequencies and sending the signal to the ECM. The oil pressure sender shows resistance to ground and is for the gauge only.

Describe "not running well". Does it start normally? Does it idle smoothly? Does it stumble upon soft, or hard acceleration? (need to be specific) Does it not go above a certain RPM? Does it run smoothly, or rough, and at what RPM? Does it start normally, but not when hot?

turbozinke
04-09-2012, 11:49 AM
THanks Jim!

Here's a pic of the wires. Two of them go to the temp sensor and the other one with a boot on it doesn't go anywhere? When I say running badly I mean that it doesn't idle and when you give it the gas you have to ease it on very lightly or it will die. When it gets revved up it runs fine. I had about 1500lb in the boat ran for 2.6 hours and used 25 gallons of gas, and top speed was 38mph. Seems a little excessive on the fuel consumption to me. Here's a pic of the wires running to the temp sensor

JimN
04-09-2012, 12:39 PM
That's the right harness- does the exhaust smell strongly of gasoline? If so, check for codes. If you have a cheap code scanner, you can us it, even if it's only the metal piece with two prongs on the end. If you don't see any codes, check the fuel pressure. If the pressure isn't adequate, you'll starve the engine at higher RPM and the fuel won't atomize properly at any speed, so idle will be crappy, too.

You need to realize that a hull made for going on-plane will be very inefficient when it's loaded down with ballast. A hull is like a wing, inverted. If you add weight, you'll need to go faster just to go on-plane and it will require more fuel to go ANY speed. Weight adds drag and a planing hull is only efficient when the boat is on-plane. Also, look at the boat's weight capacity and make sure you don't exceed it. Where the ballast is located is probably as important as the actual weight. Optimize location and your economy will improve a bit, but don't expect it to not use a bunch of gas when it's loaded.

turbozinke
04-09-2012, 03:05 PM
I don't think it is starved for fuel because it runs fine once it's revved up. I'm thinking that the ecm doesn't know what the true engine temp is and therefore the fuel mapping is incorrect. Is there not a specific amount of voltage that runs to the temp sensor? I read on another post that his is outputting 9V at 75 degrees at the gauge, but if i'm only inputting 5V then I can't output more that 5V. I only have 5.3-5.6 volts (constantly fluctuating) at the gauge. I put a cigarette lighter on the sensor and the voltage did not change at the gauge, just stayed 5.3-5.6

JimN
04-09-2012, 04:04 PM
I don't think it is starved for fuel because it runs fine once it's revved up. I'm thinking that the ecm doesn't know what the true engine temp is and therefore the fuel mapping is incorrect. Is there not a specific amount of voltage that runs to the temp sensor? I read on another post that his is outputting 9V at 75 degrees at the gauge, but if i'm only inputting 5V then I can't output more that 5V. I only have 5.3-5.6 volts (constantly fluctuating) at the gauge. I put a cigarette lighter on the sensor and the voltage did not change at the gauge, just stayed 5.3-5.6

You can't know if it's not starving unless you check the fuel pressure and revving it without a load means. nothing. The control voltage to the senders is 5VDC, not 12VDC. Also, a lighter isn't going to work because it's not a sender- all it does is get hot when it's connected to DC voltage.

If you want to find out whether the ECM is seeing the correct resistance, check for codes or connect it to a diagnostic computer. Anything else is just guessing

willyt
04-09-2012, 06:24 PM
While I don't have anything to add on the electronics part of this thread, 9.6gph in a 205V hull isn't right, with any amount of ballast at very, very max you should run 7 (granted, 2.6 hours is a pretty small sample size)

turbozinke
04-10-2012, 12:35 AM
Thanks Jim. The boat ran fine once it was revved up even with a full load (10people) it was just hard to get it off of idle. I'll try to get a diagnostic computer on it tomorrow. I meant that I took the sensor out of the engine and put a lighter on it to heat it up just like the engine would, but I didn't get a change in voltage at the gauge. Do you know what the voltage is supposed to be at the gauge at 70 degrees for instance?

JimN
04-10-2012, 12:49 AM
Thanks Jim. The boat ran fine once it was revved up even with a full load (10people) it was just hard to get it off of idle. I'll try to get a diagnostic computer on it tomorrow. I meant that I took the sensor out of the engine and put a lighter on it to heat it up just like the engine would, but I didn't get a change in voltage at the gauge. Do you know what the voltage is supposed to be at the gauge at 70 degrees for instance?

Yeah, I figured that out a little while ago. DOH!

Measure the resistance- that's what causes the return voltage to change. It should be above 10K Ohms- do a search here for this. A resistance chart ws posted. If you can't find that, google search for it.

turbozinke
04-11-2012, 10:33 AM
I found the resistance chart and I think my sensor is good. I'm going to hook it up to a diagnostic scanner. Same as a car right? I found a plug by the ecm, but it wasn't the same shape as a car. Do I need a special adapter or am I looking at the wrong plug?

JimN
04-11-2012, 11:00 AM
I found the resistance chart and I think my sensor is good. I'm going to hook it up to a diagnostic scanner. Same as a car right? I found a plug by the ecm, but it wasn't the same shape as a car. Do I need a special adapter or am I looking at the wrong plug?

If it's a 2000 model, you could use a paper clip, if you want. Bend it into t U and insert the ends into terminals A and B, then use the check engine light to count the flashes after turning the key to ON. If you only see 1 flash, a short pause and then 2 flashes, repeated three times (this represents 12) and no other codes when the three 12 flashes are repeated, your sender is fine and you need to look somewhere else, like fuel pressure. If you don't see the check engine light flash this sequence, you'll need to use a test light to connect terminals E and F so the light can be your indicator.

The first thing we were told at MC training was "If you have a drivability issue, check the fuel pressure. At the time, they told us that 80% of all issues were fuel-related and since old fuel or fuel with ethanol are known causes of fuel pump problems, this is the first place to look, not the sensors or codes. While it's possible that you have a code, it's far less likely that you have a bad sensor.

If you do see that codes have been stored, post them here.

Was the engine dropped in with the whole harness/ECM, or are you using the harness/ECM from the original 2000 engine for the 2006? If it is the old one and the engines are different (meaning, if the 2000 was TBI or LTR and the 2006 is the MCX or something completely different from the original), the ECM should be re-programmed because these were programmed based on the specific boat/engine combination. It's not a generic program, like many other manufacturers use.

turbozinke
04-11-2012, 03:36 PM
It's not the old wiring harness. I bought the complete indmar engine with computer and everything out of a wrecked 2006 Malibu, and installed it myself. I used the boat 10 times last summer with no trouble, but then it died on me out on the water because it wasn't' pumping fuel. I pulled the fuel pump and the nylon tube at the top was kinked. I replaced it, and used the boat again with no trouble. Then this spring the boat ran ok but then the trouble started later in the day. It's hard to think its the fuel pump because it runs fine under heavy load. Just has trouble coming off of idle. I'm kinda thinking it might be timing? Can this engine be checked with a paper clip? It's a regular 2006 310hp indmar.

JimN
04-11-2012, 04:14 PM
It's not the old wiring harness. I bought the complete indmar engine with computer and everything out of a wrecked 2006 Malibu, and installed it myself. I used the boat 10 times last summer with no trouble, but then it died on me out on the water because it wasn't' pumping fuel. I pulled the fuel pump and the nylon tube at the top was kinked. I replaced it, and used the boat again with no trouble. Then this spring the boat ran ok but then the trouble started later in the day. It's hard to think its the fuel pump because it runs fine under heavy load. Just has trouble coming off of idle. I'm kinda thinking it might be timing? Can this engine be checked with a paper clip? It's a regular 2006 310hp indmar.

Now that I know the ECM and harness aren't from a 2000 model, I would contact Indmar to find out if it can be read that way. My gut says no.

Did the Malibu have catalytic converters and/or O2 sensor? If it did and you removed them, that's a major reason it's not running right.

The Mastercraft has an in-tank fuel pump and it doesn't like (meaning it won't survive) running out of gas. If you did this, check the fuel pressure because I can guarantee that the pump won't be long for this world. What kind 0pf fuel pump did the Malibu have? If it's not the in-tank type, you need to find out what the recommended fuel pressure is.

I suspect there's more info that should be made known if this is to be diagnosed but at this point, I would recommend reading the codes- again, contact Indmar or a Malibu dealer to find out how. Also, I would recommend taking a fuel sample- you can do this at the Shrader valve used for checking the pressure if you have a fuel pressure gauge with the bleeder valve by collecting fuel into a known clean container, either by turning the key ON and using the pump priming cycle or while it's running. Let the sample sit for a half hour and see if it has water in it. You'll know if it does- it will either be cloudy or you'll see water droplets settle to the bottom.

BTW- if the Malibu that was the donor for this engine doesn't have a similar hull to your MC, it may not perform as you want. A hull from one company will have very different characteristics WRT hydrodynamics when compared with a hull from another manufacturer. This isn't like taking an engine from one car and slapping it into another car of similar weight and with the same transmission.

turbozinke
04-12-2012, 08:05 PM
The motor in the boat was performing great. Since the old motor was an indmar just like the new one it just bolted right up and I used it all last summer with no problems.

I checked the fuel pressure. It primed up to 75lb before I stared it, and then 85 when it was running.

turbozinke
03-15-2013, 01:29 PM
Well I never posted how I fixed the boat, and you guys helped me a lot. Here is what I found. I had the original fuel pump that came with the boat 2000 205V, and that original fuel pump had a return line that hooked up to the fuel rail. The new engine did not. The new engine was designed to have a pump that had a return in the fuel tank. So my old pump was flooding the engine by giving it 85lb of pressure. I bought a new pump for $350 online, and sold my old one for $200. Pretty good deal for me. Thanks for your help!

turbozinke
04-02-2013, 07:54 PM
OK well it's a year later and now I'm ready to finish fixing my boat to get ready for summer. I have 3 gauges that don't work. Temp, oil pressure and fuel. I'm about to take the dash apart because it's been a whole year and I can't remember where I left off. I just know the gauges don't work.