need an expert...5.7L EFI rich running

I have two questions. First, i am having rich/black smoke issues at idle and fouling plugs. I have a 2000 5.7L EFI mercruiser.

#1. I am trying to check timing. I have a marine code reader and have set the engine in base timing mode. I have aimed the timing light at the proper spot and have found only a VEE notch with no incremental degree rating. The timing dash lines up to the starboard of the vee. How do I know that this is 8 degrees btdc where it is supposed to be? Did they set up this engine to line up with the notch? I have NO numbers to reference?? I hate to just move the distributor without a baseline.

#2 When i mechanically move the throttle into a position past idle, maybe 20% of total, the throttle revs past 3000 and feels like it would keep going up like the Throttle position sensor is not working properly. I read that a malfunctioning TPS will mess with idle and could be causing fouled plugs/black smoke?

I just changed distributor, ignition sensor, and rotor.

thanks

Re: need an expert...5.7L EFI rich running

you are going to need an advance timing light to correctly set timing

you are going to need a DDT or CDS to read the codes on the computer, this will tell you if you have a sensor fault due to malfunction, perhaps causing the rich running condition

yes a faulty TPS can cause the rich running condition but be sure before you start buying parts

Re: need an expert...5.7L EFI rich running

Very seldom have I had an EFI system fail that actually set a code. You MUST have a scan tool of some sort to read the outputs of the sensors, along with fuel pressure gauges, proper timing lights, DVM's with proper test leads, along with the OEM service manual. Without them or the knowledge to use them and you are down to throwing parts/money at it and hoping to fix the problem.

The Mercruiser Scan Tool/ Tech mate scan tool (same thing different decals) will do everything the big guns do, just slower and cheaper.
http://216.230.203.183/marine/marine.htm

Re: need an expert...5.7L EFI rich running

Is it running dead rich and fouling spark plugs real bad with in 1 to 4 minutes of running and you see rich/black smoke issues at idle as soon as you start it up in the exhaust water And filling the air around you with smoke, And does it idle rough and hi or low.??? If it is then more then likely the MAP sensor is bad. And if no it is not that bad then It would be something eles, Like maybe you have noticed the engine temp takes longer to warm up more then normal?

Re: need an expert...5.7L EFI rich running

At higher throttle it seems to run with less smoke even at the dock.

thanks for your replies. looks like i will be spending more on the more advanced sensor reader than just the code mate.

Re: need an expert...5.7L EFI rich running

sorry to bug, but what is the difference between an advance timing light and the one i have from craftsman?

Re: need an expert...5.7L EFI rich running

turfguy1969 said:

sorry to bug, but what is the difference between an advance timing light and the one i have from craftsman?

Click to expand...

The advance timing light has a dial on it and All you do is point the light at the [V] on the engine and turn the dial till you find the big thick line on the balancer, [that you should paint white before you start the engine up] and line up the line to the [V] then look at the number on the light and that will be what your timing number is set at, and then you put the light to the number you need, and adjust as needed, by turning the [dist] to reline the line up at your set number you need it to be at. Also you should be able to turn the engine over slowly and line up the line on the balancer with in the [v] area, And clean the balancer up around the big line and you normaly can see some type of little lines, or numbers, or letters on the balancer so you can get a better idea of what is going on down there, But I believe there was a few years they stop putting some of the lines on the balancer for some reason. Good luck with it.

Re: need an expert...5.7L EFI rich running

Let me tell you BOAT TECK that is super helpful!! I have read the manual for this engine on this web sight, i have the Seloc book, and neither of these said anything about this set up!! It is a plastic looking VEE notch that needs to line up. I thought i was losing my mind from all the blood rushing to my head leaning over that thing.

Re: need an expert...5.7L EFI rich running

You need to manually test some of you're sensors (disconnect you're wiring harness and check with a multi-meter.

Here's a list of possible causes for running rich with EFI.

#1. coolant temp sensor (the computer gives more fuel to a cold engine)
Disconnect the sensor, test with a multi-meter (ohms). You should be able to cross reference the readings with the manual.

#2. TPS. There are lots of different ways to test a TPS, but here is the only PROPER way to test it.

The TPS is a potentiometer, and may have "dead spots"

You need a 9v battery, a multi-meter, some tape and some wires.

The TPS will have 3 pins, you need to connect them like this.

Pin 1: - side of the 9v battery and the common on your multi-meter (black)
pin 2: the volts on your multi-meter (red)
pin 3: + side of the 9v battery

Put you're multi meter in DC volts mode.

You should have a perfectly linear scale between 0 and 9 volts with 0 - 100% throttle.

So have someone move the throttle while you're looking at the multi-meter, at 50% throttle, you should have 4.5 volts....

If you see the volts go to 0 at any point (other than 0% throttle) you're TPS is toast.

Trying to measure a TPS with just ohms will not give a good reading, you MUST measure the voltage drop across the pot.

Other sensors to test:

MAP - These work the same way the TPS does, except the scale is linear with absolute vacuum. I believe most sensors are 0 - 2 bar (Absolute vacuum to 14.7 PSI of pressure)

So you would connect you're test rig the same as the TPS, but you would need a vacuum pump (hand pump) to apply vacuum to the sensor and watch the voltage swing.

There is a nice chart here that shows the voltage output of a working map sensor

(usually these sensors take 5 volts, but because we're using a 9v battery, you will be seeing 9v)

Air temp sensor (2 pins, same as coolant temp sensor)



MAF (not sure if you're boat has one of these, and they are difficult to test.)


IT could also be you're fuel pressure regulator, or even the ECU itself.

good luck, let us know.

Code readers only tell you what the ECU thinks is wrong, you need to test the sensors to know for sure.

IF everything checks out, try disconnecting the ECU and testing the sensors again from the ECU connector (you will need an ECU pin-out) it may be that you have a wiring harness issue.

Re: need an expert...5.7L EFI rich running

great info on testing the sensors! Now i wish we had the final results.

Re: need an expert...5.7L EFI rich running

It is now a year later. I did some preliminary cleaning/blowing out of each sensor before we put it in the water this year. I found the MAP sensor had a good bit of gunk and oil in it which I cleaned out. I added Lucas fuel injector treatment before we put the new fuel in. I have not had the black smoke yet this year after 8 or 10 times out. (hear that? it was me knocking wood) It still smells a bit rich, but as a friend told me these have no emission control or catalytic converter so it is going to have some fumes like an old truck or car would. Thanks for the help.