[Evolrider]

Had some issues yesterday at the lake. My boat has a 509 ci with Arizona Speed Fuel injection. I shut down the motor, and when I started it back up, it would idle, but if I tried to accelerate, it would fall on its face and back fire through the flame arrester, and then die. After starting it again, it was idleing rough, and could smell quite a bit of fuel.
Anybody got an ideas?
Thanks.

 

[ap67et10]

is this the tune port/ram jet style setup? are you running an o2 or no? would it run at all if you got the rpm up or did it seem to be worse?

first thing that comes to mind would be the map sensor. i'd imagine you are running a gm style map that bolts to the side of the intake. if this goes bad typically they go pig rich. I would first pull the plugs and make sure you are going real rich. (like you implied in your post)

AP

 

[motormonkey]

Call AZ Speed and Marine. They know what they are doing and will be able to help you the best, since its thier set up.

 

[Evolrider]

is this the tune port/ram jet style setup? are you running an o2 or no? would it run at all if you got the rpm up or did it seem to be worse?

first thing that comes to mind would be the map sensor. i'd imagine you are running a gm style map that bolts to the side of the intake. if this goes bad typically they go pig rich. I would first pull the plugs and make sure you are going real rich. (like you implied in your post)

AP

Thanks for the reply. Its AZSMs tuned port setup without an O2 Sensor. I went back down to the Marina, and pulled the plugs, and they were shiny wet with gas. Is there a way to test the MAP sensor?

 

[ap67et10]

Thanks for the reply. Its AZSMs tuned port setup without an O2 Sensor. I went back down to the Marina, and pulled the plugs, and they were shiny wet with gas. Is there a way to test the MAP sensor?

yes and its really pretty easy. first you will need to know whether its a 1 bar map sensor or not. most likely it is, if it N/A engine. you will also need a vacuum gauge (might be able to tell without one) or vacuum pump (easier) and a volt meter.

a map sensor is simply a vacuum gauge with variable output voltage based on vacuum reading. typically you will see .5 v (on the feedback wire) at highest vacuum and 4.5-4.9 v at atmosphere (if its a 1 bar map sensor). the quickest check to see if its completely done would be to check the voltage on the signal/feedback wire when the key is on, and the engine is NOT running. your signal wire should be the center wire of the 3. you can check this quickly by removing the connector and checking the outer ones which should be 5v reference on one, and ground on the other. easiest would be to put one test lead on one outer pin, and the other lead on the other outer pin. if it reads 5 volts then your center pin is in fact the feedback/signal wire.

for the actual testing part you will plug the connector back in and backprobe the center pin (you need to make sure it is actually hitting the pin otherwise it will throw you way off) then put your other test lead on ground. you should see somewhere in the 4.3-4.9 v range on that wire with the key on (again this is only for a 1 bar map sensor). if you see less say 1-4v you probably have a bad map sensor (as long as you have good contact on ground and center pin that is backprobed). check this first and find out what it is telling you.

does this make sense? do you have a vacuum pump or guage to use, you will need it if your reading above are correct.

AP


one thing is that in your case with super rich condition, you will most likely not see a problem with the readings when the engine is not running. you will probably find good readings doing what i said above and you will need to check the voltage from the signal wire when the engine is running or better yet in a induced test with a vacuum pump. which is a much easier method because then the engine does not need to be running. you can simply create a vacuum on the sensor and as you release the vacuum you should be able to watch the voltage go up.

 

[Beer:30]

Also check your TPS. The throttle position sensor internal return spring broke on mine. The TPS stayed at 3/4 throttle. So, it was dumping fuel in for 3/4 throttle while at idle. Spuddering and rich exhaust smell. Pretty common. I have replaced two other TPS units for other people that were having similar issues on cars. One was GM and the other was Chrysler.

 

[Evolrider]

Also check your TPS. The throttle position sensor internal return spring broke on mine. The TPS stayed at 3/4 throttle. So, it was dumping fuel in for 3/4 throttle while at idle. Spuddering and rich exhaust smell. Pretty common. I have replaced two other TPS units for other people that were having similar issues on cars. One was GM and the other was Chrysler.

Thanks for the reply, I disconnected the TPS and the engine would rev up and down between 1200-1800 RPM range, and when I plugged it back in, it would fluctuate between 500-900 RPM. and as soon as you try to accelerate off idle, it would die.

 

[Beer:30]

Thanks for the reply, I disconnected the TPS and the engine would rev up and down between 1200-1800 RPM range, and when I plugged it back in, it would fluctuate between 500-900 RPM. and as soon as you try to accelerate off idle, it would die.

Have you checked your fuel pressure? That's usually first, is to make sure the pressure is where it's supposed to be.

Speaking of which; check the vac line that goes to the fuel pressure regulator. If it was off, that would cause a lean-sputter-spit (vacuum leak) and also cause a rich condition.

 

[Evolrider]

yes and its really pretty easy. first you will need to know whether its a 1 bar map sensor or not. most likely it is, if it N/A engine. you will also need a vacuum gauge (might be able to tell without one) or vacuum pump (easier) and a volt meter.

a map sensor is simply a vacuum gauge with variable output voltage based on vacuum reading. typically you will see .5 v (on the feedback wire) at highest vacuum and 4.5-4.9 v at atmosphere (if its a 1 bar map sensor). the quickest check to see if its completely done would be to check the voltage on the signal/feedback wire when the key is on, and the engine is NOT running. your signal wire should be the center wire of the 3. you can check this quickly by removing the connector and checking the outer ones which should be 5v reference on one, and ground on the other. easiest would be to put one test lead on one outer pin, and the other lead on the other outer pin. if it reads 5 volts then your center pin is in fact the feedback/signal wire.

for the actual testing part you will plug the connector back in and backprobe the center pin (you need to make sure it is actually hitting the pin otherwise it will throw you way off) then put your other test lead on ground. you should see somewhere in the 4.3-4.9 v range on that wire with the key on (again this is only for a 1 bar map sensor). if you see less say 1-4v you probably have a bad map sensor (as long as you have good contact on ground and center pin that is backprobed). check this first and find out what it is telling you.

does this make sense? do you have a vacuum pump or guage to use, you will need it if your reading above are correct.

AP


one thing is that in your case with super rich condition, you will most likely not see a problem with the readings when the engine is not running. you will probably find good readings doing what i said above and you will need to check the voltage from the signal wire when the engine is running or better yet in a induced test with a vacuum pump. which is a much easier method because then the engine does not need to be running. you can simply create a vacuum on the sensor and as you release the vacuum you should be able to watch the voltage go up.

Unfortunatly I dont have the required tools to test it with me, but I think based on what you are discribing, it sounds like the MAP sensor. I think that I will just pick one up in the morning.
Without driving 15 miles back to the marina would you have an idea what sensor I have? I tried to call AZSM, but the lines where busy. The motor is a Paul Pfaff 509 with AZSM complete injection system on it.
I have three more days at the lake, and whould love to get my Hallett back out.

Thanks for all the info.

 

[ap67et10]

ok, this is what you will need. look at the number on the top of your map sensor. there are 3 numbers then a gap then 4 numbers. the first 3 numbers tell you how many bars it reads. if it is: 039, 460, 883 or 876 its a 1 bar. if it is: 886, 012, 539, 609, 701 its a 2 bar. and the likely hood of you having a 3 bar is pretty much non-existant, so i won't even list those. I would guess you have the 039 map sensor. if you get another one you should be able to ask for a 91-96 chevy truck 5.7L map sensor and it should plug right it and work perfect....as long as this is your problem. it sounds to me like it is very likely this is your problem, and its pretty cheap and easy to just buy one to see if you can get it back on the water. should be around 50-60 bucks i would think. Hope it works out for you and hope this info helps.

AP

 

[Beer:30]

Good advice. I doubt there would be anything other than a 1-bar, either. 3-bar would be for super/turbocharged applications. Have one on my Buick Grand National.

 

[Evolrider]

ok, this is what you will need. look at the number on the top of your map sensor. there are 3 numbers then a gap then 4 numbers. the first 3 numbers tell you how many bars it reads. if it is: 039, 460, 883 or 876 its a 1 bar. if it is: 886, 012, 539, 609, 701 its a 2 bar. and the likely hood of you having a 3 bar is pretty much non-existant, so i won't even list those. I would guess you have the 039 map sensor. if you get another one you should be able to ask for a 91-96 chevy truck 5.7L map sensor and it should plug right it and work perfect....as long as this is your problem. it sounds to me like it is very likely this is your problem, and its pretty cheap and easy to just buy one to see if you can get it back on the water. should be around 50-60 bucks i would think. Hope it works out for you and hope this info helps.

AP

Thanks for all the info... I will have to go down to the marina in the morning, and get some numbers. I have my fingers and toes crossed that this is it. I will keep you posted.
Thanks again...

 

[Evolrider]

Have you checked your fuel pressure? That's usually first, is to make sure the pressure is where it's supposed to be.

Speaking of which; check the vac line that goes to the fuel pressure regulator. If it was off, that would cause a lean-sputter-spit (vacuum leak) and also cause a rich condition.

Thanks for the info. I didnt check the fuel pressure, because everything I need is at home, but have replaced the MAP sensor, and that wasnt it. I was going to change the TPS sensor also, but the local dealer didnt have it in stock, and I am heading back home tomorrow. It will drive in idle with the gear engaged for about 3 minutes, then it just floods itself out. I am going to check the fuel pressure regulator when I get home, and check out the TPS. I spent about an hour with an oar today, trying to get the Hallet to the ramp.

 

[ap67et10]

Thanks for the info. I didnt check the fuel pressure, because everything I need is at home, but have replaced the MAP sensor, and that wasnt it. I was going to change the TPS sensor also, but the local dealer didnt have it in stock, and I am heading back home tomorrow. It will drive in idle with the gear engaged for about 3 minutes, then it just floods itself out. I am going to check the fuel pressure regulator when I get home, and check out the TPS. I spent about an hour with an oar today, trying to get the Hallet to the ramp.

I'm sorry to hear that didn't work out. Its tuff not having the tools easily available to get the right diagnosis. I was thinking about your situation and like beer said you may have a throttle issue, but it should get better as rpm goes up i would think, but maybe not. i would try one other thing, if i were you, before buying more things.

Another thing that would cause this is if the coolant temp sensor went open circuit, now the biggest problem is that this could also have happened anywhere in the harness. if the coolant temp sensor goes open circuit or in the harness where the ecm is reading the coolant temp as open circuit then it essentially is reading -40 degrees. this would cause the ecm to command an extremely rich condition and would add more and more fuel as rpm and load increase. this would be very similar to what a bad map would do.

the way to check this would be to pull the coolant temp sensor connector off and jump the two wires together. this should give the ecm an input that would relate to about 240-250 degrees, but should run, and run way better. this will tell you if you have a bad sensor only. if this doesn't do anything than it still could be in the harness and you would need to find the 2 wires that go directly into the ecm from the coolant temp sensor. you would then check continuity of the two right at the ecm when you have the wires jumped...or connected, but the readings should never go OL or OFL (depending on the meter) try this...it is free...well to check it is, and you wouldn't waste money if its not the problem. hope you get back on the water.

AP

 

[Evolrider]

I'm sorry to hear that didn't work out. Its tuff not having the tools easily available to get the right diagnosis. I was thinking about your situation and like beer said you may have a throttle issue, but it should get better as rpm goes up i would think, but maybe not. i would try one other thing, if i were you, before buying more things.

Another thing that would cause this is if the coolant temp sensor went open circuit, now the biggest problem is that this could also have happened anywhere in the harness. if the coolant temp sensor goes open circuit or in the harness where the ecm is reading the coolant temp as open circuit then it essentially is reading -40 degrees. this would cause the ecm to command an extremely rich condition and would add more and more fuel as rpm and load increase. this would be very similar to what a bad map would do.

the way to check this would be to pull the coolant temp sensor connector off and jump the two wires together. this should give the ecm an input that would relate to about 240-250 degrees, but should run, and run way better. this will tell you if you have a bad sensor only. if this doesn't do anything than it still could be in the harness and you would need to find the 2 wires that go directly into the ecm from the coolant temp sensor. you would then check continuity of the two right at the ecm when you have the wires jumped...or connected, but the readings should never go OL or OFL (depending on the meter) try this...it is free...well to check it is, and you wouldn't waste money if its not the problem. hope you get back on the water.

AP

Thanks for that piece of info... I would have never even thought of that. Once I get it home tomorrow, I will have everything I need to try to diagnose the problem. I was trying to get it going with the info that you guys have fed me, and a leathermen, and a Crescent wrench. Next time I go out, i will leave that extra 30 pack of Coors Light out of the back of the truck, so I have room for a tool kit.
Thanks for all the info, and I will keep you posted of my findings.

 

[dynoguy]

AZSM is out of business..... I have a shop in Gilbert,AZ and I have all the necassary scanning equiptment to diagnose your hot rod. Let me know if I can help in any way. Mark c/o Speed Sports 480-539-4842

 

[ap67et10]

AZSM is out of business..... I have a shop in Gilbert,AZ and I have all the necassary scanning equiptment to diagnose your hot rod. Let me know if I can help in any way. Mark c/o Speed Sports 480-539-4842

I'm not suprised

 

[ibelio]

also check fuel press regulator. diaphram breaks will suck fuel into engine to run rich/flood

 

[Evolrider]

TPS install

How should my TPS be set up?? what should the resistance be at throttle closed, or wide open?
Thanks.

 

[Beer:30]

How should my TPS be set up?? what should the resistance be at throttle closed, or wide open?
Thanks.

I don't know the ohms, but it is a 5V reference. WFO should be showing real close to 5V. 4.85 at LEAST. Idle will probably be .50 to .60