Poor idle

Need some help please on my 89’ SN with PCM 351. Having some issues with my SN idling and it is often difficult to start and keep running at idle especially after running the engine fast. Runs perfectly at mid-range and top-end. To start it, I often have to pump the throttle nearly wide open after which it produces a lot of smoke (assuming that the engine was flooded?). Used Holley carb that was supposably rebuilt. I’ve set the fuel levels on both sides of carb and tried to adjust the two idle mixture screws starting at 1 1/2 turns out. When adjusting, it doesn’t seem to have any effect on rpm’s or the vacuum when hooked up to a vacuum gauge. I’m hooking the vacuum gauge in place of the PCV valve (right?) as I don’t see another source of full vacuum. Going to check today for possible vacuum leaks with propane. Also, converted to electronic ignition 4 months ago. Read through several of of the threads on this forum and before I tear into a possible carb rebuild (which would be my first time rebuilding this type of carb), is there anything else I should check? Thanks in advance! -Gene

William,
First thing to check is the float levels. Since it's dripping fuel, I'd say they are set too high. Another indicator of a flooding condition is you needing to open the throttle up nearly wide open (I'm assuming you are not "pumping" the throttle) Pumping would actually add more gas whereas opening the throttle allows more air in to overcome the rich mixture.

How's the choke working both hot and cold?

Also buy yourself one of the many Holley carb books that are out there

Check the link for some examples

You'll learn a lot from any of them. Plenty of pictures and good explanations and exploded views   

link

Well, guess I didn’t set the float levels exactly correct as I checked them again today and the back float level was pouring out fuel from the level drain. I reset the level again and the issue of the dripping fuel into the venturi’s ceased and engine started idling as it should. Will water test it again tomorrow. Thanks for all the help.

Is the carb list # 50463
0909 the same as Holley 4150 or 4160? Want to ensure that I’m buying the right book.

Maybe a picture of this carburetor and what you're doing to adjust the floats would be good

Seems so

My 2nd last fuel pump puked two check valves in the same moment and stopped me dead
Its replacement had fuel out the vent just prior to my engine work last fall.

Form out data points, they don't make them like they used to. Mine were the brandless, two from skidim, one from summit. mIss the original carter, lasted 30+ seasons

Appears Fuel Pump is the new weak link on these engines

KENO wrote: Well that sounds like 2 strikes against the Carter M60389. It's pretty hard to install one wrong so it's probably not you causing the problem. As mentioned in your previous thread, there have been diaphragm issues Where are you buying these pumps, Joe's surplus fuel pump emporium ? You could try for 3 strikes or you could try a Sierra 18-7267 fuel pump. It's a copy of the AC dual diaphragm pump for a 351W and nobody seems to be grumbling about them. The suction and discharge are in slightly different locations. Suction side is easy, but if you have metal between the pump and the carburetor, some bending or a new line would be needed. No guarantees, but I'd go this route before electric. Plenty of mechanical pumps running just fine out there. link AirTex also sells a 60389 which may or may not come from the same place the Carter's do BTW how's the vibration issue from your vibration thread?

HA! Surplus Fuel Pump Emporium...from Amazon. I called Carter's technical assistance line today and it appears some earlier versions of this pump were defective. They are overnighting to me a "new and improved" version (new stock?). Going to try it one more time and if it happens again, will definitely go with the AC version.

As for the vibration issue, seems to be much better now. I checked the shaft coupler/trans flange alignment 3 times to ensure it was w/i the .003 spec. Adjusted the carb which resulted in the engine running smoother (outside of the flooding caused by the fuel pump issues) and this has fixed most of the vibration. I think any vibration now is normal as part of the Harmonic balancer as mentioned.

I am getting some whining noise at idle at first start-up just in front of the trans but it's not coming from the trans. Maybe the damper plate? Seems to go away when warmed up. Also, leaking a small amount of oil below this area towards the rear of the engine. I noticed that one bolt connecting the bell housing appears to be stripped which may be causing the seal to leak. Will dig a little deeper into this.

Slowly getting these issues fixed on this 30 year old girl! Up to the final run last night and the fuel pump issue, she ran like a champ!

Assuming they don't want the bad one back, why don't you remove the housing and see what the diaphragm looks like.

A picture would be good.

The bad ones seem to have a shiny diaphragm ( a neoprene coating over fabric) that peels and cracks easily.

Glad they're sending a new one to ya'

bfootr wrote: leaking a small amount of oil below this area towards the rear of the engine. I noticed that one bolt connecting the bell housing appears to be stripped which may be causing the seal to leak. Will dig a little deeper into this.

William,
There isn't a "seal" between the bell housing and engine. Oil at that point is ether engine oil or trans fluid. What color is the oil?

8122pbrainard wrote: bfootr wrote: leaking a small amount of oil below this area towards the rear of the engine. I noticed that one bolt connecting the bell housing appears to be stripped which may be causing the seal to leak. Will dig a little deeper into this. William, There isn't a "seal" between the bell housing and engine. Oil at that point is ether engine oil or trans fluid. What color is the oil?

It's definitely brown engine oil.

bfootr wrote: So as long as I reference the List # 50463, I should be able to get the right rebuild kit?

No, it will have the wrong needle and seat assemblies.

I can come up with a number that should work for you later today.

As far as the oil, the good news is that your transmission isn't leaking assuming it has red transmission fluid in it. An 89 with the PCM 1.23 to 1 transmission had brown 20 weight oil originally and maybe that's what's still in it.

That means there must be bad news though.............the rear main seal on the engine is probably leaking if it's not the transmission leaking.

bfootr wrote:     What's involved in replacing the rear main seal?

Pulling the engine and removing the oil pan. Some have they have done it with the engine in the boat by raising the aft end of the engine so the pan can be dropped. In my mind, that would be a real PITA.

8122pbrainard wrote: bfootr wrote:     What's involved in replacing the rear main seal? Pulling the engine and removing the oil pan. Some have they have done it with the engine in the boat by raising the aft end of the engine so the pan can be dropped. In my mind, that would be a real PITA.

Don't listen to Pete

Your engine being an 89 has a one piece rear main seal and it can be done in the boat without removing the oil pan.

Also being an 89 it's normal rotation and a regular automotive one piece rear main seal will work just fine

You'll still have to jack up the back of the engine enough to remove the transmission, then the bellhousing and the flywheel.

Then you'll be staring right at the rear main seal.

It's only a mild PITA

Here's a bit of a guideline from another thread

This was to access the damper plate so in addition to what's listed here, you remove the damper plate and the flywheel to get at the rear main seal

KENO wrote: Here's a set of instructions for ya Remove the motor box and the rear floor piece Disconnect the battery Remove the starter Remove the wires from the Neutral Safety Switch Disconnect the shift and throttle cables Unbolt the coupling and slide the shaft back as far as it will go Unhook the water hoses from the transmission cooler, leave the oil lines hooked up and unbolt the cooler bracket from the bellhousing. The cooler will stay with the transmission. Loosen the pinch bolts on the front motor mounts so the engine can pivot on the mounts. Make sure the bolt is loose and not still tight when the nut is backed off. Leave the rear mounts hooked to the transmission and remove the mounting fasteners from the stringer/cradle. It's a little heavier this way but it's easier to wrestle the transmission around with the mounts on it. Unhook the exhaust hoses wherever it's the easiest for you..Depending on the hoses it might be easier for you to remove them as the engine is being raised Raise the rear of the engine with a bottle jack under an exhaust manifold or use a hoist or whatever other lifting means you have till the engine is about level and block it so it can't fall and ruin your day. Unbolt the transmission from the bellhousing. You probably have 2 bolts and 4 studs holding it on. Slide it backwards till it;s off the studs and set it on a piece of plywood where the rear floor panel was. To me it's easier this way than taking the bellhousing off at the same time Now unbolt and remove the bellhousing, don't forget the little bolts holding the splash shield in place. Unbolt the old damper Bolt the new one on Some people will tell you to tighten the bolts now, some will work thru the starter hole with a crow's foot, u joints etc to tighten them after the transmission is installed and some drill a hole in the bellhousing to tighten the bolts after the transmission is installed. It's your call here on what you want to do. Grease up the female splines Bolt the bellhousing and splash shield back on. Some people bolt the bellhousing to the transmission and install the whole thing at once but it's a whole lot easier to wrestle the 100 or so pounds into place when you can slide the transmission on the 4 studs to get the shaft into the splines. Slide the transmission into place (sounds so easy but you may have to rotate the shaft some to get the splines lined up along with a little lifting. That's why sliding it on the 4 studs is easier. And if you don't have studs, then do what Duane mentioned in the previous post. From here you're just reassembling in reverse order and if you have corrugated exhaust hoses it's easiest to hook them up again as the engine is being lowered. And..........don't forget to check the alignment or somebody named Pete will be all over you I figure somebody will come along and tell you how they did this or that different but this works pretty smoothly with the least amount of wrestling involved..