1999 5.0GI running rich, exhaust smoke and soot, TBI question

[firebird1158]

I have been getting a rich exhaust smell for a while now and some smoke at start up and now seems sluggish to plane but once rpm get up it seems to clear itself.... I have been reading alot of posts on this symptom and from what I gather the usual causes are either the IAC solenoid or the TBI themselves. I have to check tomorrow to see if I can identify if the TBI are leaking and putting too much gas in or the solenoid could be stuck. I ran some fuel injector cleaner in gas and now it seems to be richer and smoking more.... which could be a leaky TBI.... My question is the TBI in these are supposed to be 80lb rated and have found some that match the part number but says they are 90lb rated. Will this matter as computer controls flow right. Maybe I wont need them but curious if the higher rated ones will work if I do

 

[dypcdiver]

I might be well off the mark but, I encountered the exact same problems which were caused by the motor running too cold i.e. 135/140 deg F. It took me a whole season to find the reason for the cold running, turned out to be a vane from the raw water pump stuck in the thermostat bypass port. The ECM was seeing a cold motor and consequently supplying a rich mixture.

 

[evantful]

We might as well make this the "1999 Volvo Penta 5.0Gi owners with rich running motors" thread.

About 2 years ago I began noticing it running very rich at idle. Runs almost flawlessly otherwise.
Did a full tune up of the usual stuff, Cap, Rotor, Plugs, Wires also replaced the MAP sensor, Coolant Temp Sensor, and PCV, but the issue continues. (I had replaced the IAC a few years before that when I had an unsteady Idle, that issue was solved)

On the Automotive side of this with the TBI's, the common parts that cause this rich at idle condition (which seems to be very common on aged TBI vehicles) are the Coolant Temp Sensor, the Map Sensor (or a bad vacuum line to the sensor) or the Fuel Pressure Regulator.

In a few weeks after a trip Im going to remove the Throttle Body and rebuild it. New Fuel Pressure Regulator (Diaphragm and Spring), send the injectors out to be cleaned and new gaskets all around. Im also going to replace a few of the vacuum hoses going to the Throttle body.

Given that the rebuild parts from Volvo Penta are non-existant, and thats mainly because GM discontinued the parts, I have been able to get most of the correct corresponding parts needed to rebuild the pressure regulator. Let know if you need any info.

 

[firebird1158]

this is from a different forum that i was reading about the same issue... people keep throwing parts and changing various items and still getting the rich situation and this person seemed to know the problem well.....

the fuel injectors are the problem. It sounds crazy but if you can find a replacement pair, just replace them. I work at a shop in New Mexico and I've had problems with 3 5.0 gi's. After swaping complete t.b.i. units (after getting my ass kicked in troubleshooting)the problem went away. I then started swapping all sensors and everything related. It still ran crappy. I then swaped the injectors and problem was solved. The next two boats with the same symptoms were also injectors. I have another boat in here now with the same problems but I can't find injectors. Talked the the volvo rep and he supposedly spoke with g.m. (being as it's a g.m. part) and he said I'm outta luck. My next bet is to purchase a throttle body or switch to carb

 

[BarryTurano]

Had the same problem with my 5.0gi. Changed every part in the system, VST, both fuel pumps, every sensor known to man, had the computer redone, replaced fuel injectors, distributor, cap, wires and rotor. Still would run incredibly rich and would bog down. Got disgusted puled the entire fuel system, replaced the new distributor with one for a carbed motor. Put on a Quadra Jet. Have been running since. My NEW mechanic (not the parts changer) told me there is a tube on the map sensor that if it is clogged would cause problems. He is probably right. Because when the map sensor was disconnected the motor ran better. If you check back under my name you will find the history of my boat. Hopefully this will help.
Barry

 

[evantful]

Hey Barry, thanks for chiming in. I actually had read your thread about a year ago when I first noticed my rich condition, you provided a lot of great info. I don't think it is as bad as yours was, mainly because it still runs excellent otherwise. Most likely we have different issues.

Just for reference sake, do you happen to remember what Injectors you purchased as replacements? Thats one area Im still trying to pin down information on


Firebird, I had come across that thread a while back, Im not sure what I make of it yet

 

[BarryTurano]

I wish I could help. But unfortunately the parts changer obtained them from someplace in Connecticut. Sorry I was not of much help. I know he sent the originals out to be cleaned. One was cleanable the other wasn't or so he said so I had him get me 2 new ones. Why not try having them cleaned before replacing them? Also make sure the fuel rail is clean also. But if you are running rich it may be something else sending a bad signal to the injectors.

 

[evantful]

Totally agree, and thats my plan first is to have them sent off for cleaning when I break down the Throttle Body for a good cleaning and replace the fuel pressure regulator

 

[firebird1158]

Well, today I called a very knowledgeable marine tech and he said the first thing to do was clean the spark arrestors... he said they become very plugged with dirt and cause rich and smoking issue. Other than that he said they could come plug computer to it and see what errors are in the ecm. So I am going to start there and check tbi for spray pattern or leaky injector while I have the arrestors off. I just had this engine replaced last season with new crate long block and everything was cleaned and checked before putting old parts back on and was running great and when the smoking started I assumed it was coming from the other old engine but i only had the new one running when I seen that it is actually the culprit not the old one. The more i read about this issue the more complex it gets.....

 

[Tail_Gunner]

If your injectors are bad you can replace them with the auto type by the way there all auto injectors, Your looking for injectors that came from the 94/95 454... that year used injectors and a fuel pressure rail rated at 30 psi they are automotive 4.3 injectors but they run at 30lbs where as in auto they run at 13psi The standard automotive brand part number is TJ-17 rated at 50lbs at 13 psi but will run quite well @ 30psi

As long as your tbi runs at 30lbs of pressure under a load your fuel pressure reg is fine.

 

[firebird1158]

Well checked over a few things today and good thing I did, had a ring clamp snapped on water pump and was leaking and tossing water everywhere!! Arrh! Easy fix, wondered why last trip the alternator was not putting out enough volts, wet belts.

Anyway to the spark arrest or, one was dirty as hell and I cleaned it but new motor was spotless, injectors seemed to be spraying ok as well. Now for the bad, I had grown oil on the new motor! Almost had a stroke as that is why I replaced engine over 1000 hr on salt water and head leaked, water jacket eaten through. So I stick oil pump in and out comes dirty, real dirty oil and low viscosity but no water , thank god!! But still what the hell. I pull all the plugs and they are all light brown. Was thinking with running rich and gas smell thT maybe I had a cylinder not firing, replaced oil, idles not as smooth as it was. I am stumped again. It has been doing this on and off since I replaced the engine last year and wondering if the guy set the timing right?? Could that do it?? But what's with the dirty oil and grew on stick, that's never good!!

Any insight would be greatly appreciated.

 

[firebird1158]

It's a 1999 boat with 5.0GI so would I have a automotive style fuel pump that could have a bad diaphram? and leaking into crankcase? What else could cause gas to get in to crankcase?

 

[bruceb58]

It's a 1999 boat with 5.0GI so would I have a automotive style fuel pump that could have a bad diaphram? and leaking into crankcase? What else could cause gas to get in to crankcase?

No, you have an electric fuel pump.

 

[firebird1158]

No, you have an electric fuel pump.

Thats what I thought but several boaters I know keep telling me to check the fuel pump. Any ideas beside the carb injectors dumping fuel? Could it be a vacuum leak at intake manifold?

 

[firebird1158]

So, update, I changed the injectors and pressure regulator diaphragm and didn't change anything, changed distributor cap and button, it was corroded bad,nothing, So ordered plug wires and today I decided to change the plugs and when got to boat and pulled first plug it was half inch shorter than my new ones??? Wtf? So did some reading arms find out my new motor has the wrong plugs, 43t not 43lts(for vortec motor). So change them out but now I'm wondering if that damaged anything, it ran good for first half of summer before I noticed rich smell and smoking and fuel in oil, changed oil and will again but but would the gas in oil cause it to still smoke? Cause it still is smoking and still smells rich... It does run better now but still has a little shake to it.

 

[alldodge]

The MAP sensor has been mention a few times by others in this thread, have you ever tested or changed it? Its a 1 bar sensor which can cause it to run rich if it is not working.

 

[firebird1158]

I switched the map sensor from one motor to the other with no noticeable difference so I think it is working fine.Sprayed carb cleaner around to try to find a vacuum leak but nothing. I put a vacuum tester on the map hose to TBI and it had about 15 reading at 1000rpm but was flickering about 2-3 on the gauge, increased rpm and it rose to close to 20 but still flickering....from what I read this would indicate a sticky valve??? here is a good article for interpreting vacuum http://www.secondchancegarage.com/public/186.cfm . I ordered plug wires but never came today.... the funny thing is if you put in neutral and rev it to about 1000 rpm and let it stay there while a little shakey it then seems to clear itself up and rpm jump up to 15-1800 and engine stops smoking and seems very responsive through rpm, but when you let off the throttle it gets boggy again and skakes a little and smokes again...... would it be a weak plug wire maybe? I'm gonna check compression tomorrow, maybe should have started there but with motor being new I figured it would be something else.

 

[firebird1158]

Well just finished a compression test and number 1 cylinder had 50 psi where as all others had 185-190 psi. I poured a little oil in the cylinder and got a reading of 55 psi. So does that mean I have a bad valve?? I took off the valve cover and the springs look ok, not really sure what to look for??? As with original issue it stinks rich of fuel and smokes out the exhaust. Should I pull the head? Don't have a leak down tester.

 

[ericga]

Very likely. With a table spoon of oil in the cylinder sitting for few minutes you should have gained more that just 5 psi. If it does leak by the cylinder it has to be either an intake or exhaust valve.

I would try a good cleaning first before pulling the head.

 

[alldodge]

Well just finished a compression test and number 1 cylinder had 50 psi where as all others had 185-190 psi. I poured a little oil in the cylinder and got a reading of 55 psi. So does that mean I have a bad valve?? I took off the valve cover and the springs look ok, not really sure what to look for??? As with original issue it stinks rich of fuel and smokes out the exhaust. Should I pull the head? Don't have a leak down tester.

You could rotate the engine so that the one cylinder is at TDC and see if the valve height are the same. If there not the same you have a bent valve or guide issue. Still looks like the head needs to come off.

The 185 to 190 psi is high for a 305, should be in the 150 range. What did the plugs look like in the cylinders