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Edelbrock 1409 - slow out of the hole, slow to respond - recent problem

brucewol

Member
Application – marine engine in a 1994 Tige Ski Boat

Engine 2010 5.7L Vortec Mercruiser

Edelbrock 1409 marine carburetor - 4 barrel with electric choke, 600 cfm, 30cc accelerator pump, "J" tubes, etc

Electric fuel pump kit - low pressure 4-7 psi electric fuel pump

Delco Voyager ignition kit - Voyager distributor with Electronic Spark Timing (EST), High energy ignition coil, 8mm marine spark plug wires and spark plugs

I replaced the original engine about 2 years ago, At that time, I spent a far amount of time to get acceptable performance by using different metering rods, jets and step up springs. Probably should have written down what I ended up with but I didn’t. Think I ended up being slightly on the rich, power side. Ran well for waterskiing where quick response is required at around 3500 RPM to maintain speed as skier pulls against boat and then relaxes pull as they turn. I’m using an automated speed control so that there is only about 20 RPM difference from the high and low RPM during normal operation.

So much for the background.

Now the engine is performing poorly. Doesn’t idle very well. Can smell gas, so must be running too rich. Pulling skier out of the water, the engine seems to stumble. Then while skiing, the engine surges. Probably the automated control wants to increase RPM but the engine doesn’t respond. So the automated control opens the throttle further and then the engine finally responds with more power then is needed.

Initially, the problem would go away after about 10 minutes of skiing. Now it happens even after 45 minutes of skiing but not constantly.

I’ve pulled the plugs – they all look good. Pulled the distributor cap – okay there also.

Did find a problem where the choke linkage became disconnected but this has been fixed. The choke does fully open when the engine warms open and this take only a minute or so.

Sprayed staring fluid on the carburetor gaskets to see if there was a vacuum leak but didn’t find anything.

I’ve ordered a carb rebuilt kit which will be here the end of the week. I’m going to open the carb up, so I’d need to at least replace the gasket below the airhorn anyway. This time I’ll write down what jets, rods and springs I’ve got. Be a couple of days before I can get to the boat.

What should I be looking for? Any troubleshooting tips?

Thanks, Bruce
 
Assuming this has been running (no changes) well and issue recently occurred, you may want to verify the float is not leaking and the needle and seat are clean and functioning.

Also make sure the mounting bolts are tight and the carb-manifold gasket is intact (and use a new one if you pull the carb).

I'd also clip a timing light on each plug lead to make sure every one is firing consistently...the spark plug leads need to be measured if there is any inconsistency in their spark.

A final check is to make sure the ignition advance (built into the module) works...a known failure mode is for the advance to be frozen.
 
Thanks for the tip. I've got the carb halves separated now. Float and needle valves look clean, jets clean. Fuel strainers look clean. I did find a small piece of debris stuck to the side in one of the float bowls. Didn't look like it was moving around. The gasket between the carb halves was scrunched a bit. I had checked for a vacuum leak by spraying starter fluid around carb but didn't find any. I'll replace this gasket as well as the one between carb and manifold when I get carb rebuild kit. Also the bolts between the carb halves while tight, were looser than I would have expected. I did take the carb apart to rejet when I first got the engine.

Here are my jets, metering rods, step up spring, accelerator pump

Main Jet 401

Secondary Jet 401

Metering Rod 7047

Step Up Spring – plain, aggressive

Accelerator Pump close to carb – aggressive

For the 1409, per the Edelbrock Calibration reference Chart, this should be Ref#20, slightly rich. Step up springs and accelerator pump are more aggressive - richer, than stock.

Once carb is rebuilt, I'll test it to see if problem has been resolved. If not, I can check plug wires easily enough. Will need to do some research to understand how to diagnose ignition advance. Think I have an old timing light and dwell tach but haven't used them in 20 years.
 
From my experience, a needle and seat that "looks clean" doesn't mean squat...I test them with a hand pump to make sure they don't leak. Floats can be observed once placed in a can of fuel or they can be weighed with a scale...I may be anal about carb stuff but I've never had any issues while out over the continental shelf.

The old fashioned timing light will be find...you can mark you existing balancer with tape and a magic marker or just buy a "timing tape". Only trick is to measure the outer diameter of the balancer.

good luck
 
Still haven’t found the problem and it appears to be getting worse. On occasion skier behind boat gets a wiff or raw gas. I’m thinking this is because gas is unburned – an ignition problem rather then running too rich. Here’s what I’ve done

Rebuilt Edelbrock 409 carb. Replaced airhorn gasket between halves and gasket between carb and riser/leveler on manifold. After putting carb back on boat, sprayed starter fluid around joints to check for vacuum leak. Blew out all passages. Replaced needle valves and seats. Set accelerator pump to middle notch – less aggressive, rich and used a slightly less aggressive step up spring – pink. Floats look okay, no sloshing fuel in them. My main jets are 401, secondary 401 and metering rods 7047. No change from before. I did find some debris in one of the float bowls that I initially thought was the cause. But after the carb rebuild and still having the problem, I think might have just been flakes from the gasket when I separated the halves.

Fuel pump. Has good voltage, 13+ when engine is running. Can hear the pump running with a sound dowel stuck in my ear. Don’t have a pressure gauge – yet.

Fuel/Water Separator – Opened this up and it looks clean. Have had this problem on several different tanks of gas, so I doubt fuel is the problem.

Plugs – pulled them all, look good, no cracks in insulation. . Slight tan color, no carbon on electrodes. Connected each plug to a timing light and observed the light at idle and 2000 RPM. No difference in any of the plugs. Pulled each plug off one at a time when at idle and engine ran rougher for each plug pulled.

Timing – Timing looked steady at idle and advanced some when at 2000 RPM. Don’t have any marks or timing tape for the balancer.

Distributor – pulled the cap, looks okay. Pulled the wire from the coil, also looks okay. Checked for 12 volts to the coil and from the ignition module. 13+ when engine is running.

Coil – used a voltmeter to check for opens, shorts per some diagnostic info I found from a Seloc Mercruiser repair manual. Checked out okay.

Not sure what my next step is. Throw new parts at it, get better test equipment or find someone with the proper diagnostic tools to take a look at it. Still haven’t found the problem and it appears to be getting worse. On occasion skier behind boat gets a wiff or raw gas. I’m thinking this is because gas is unburned – an ignition problem rather then running too rich. Here’s what I’ve done

Rebuilt Edelbrock 409 carb. Replaced airhorn gasket between halves and gasket between carb and riser/leveler on manifold. After putting carb back on boat, sprayed starter fluid around joints to check for vacuum leak. Blew out all passages. Replaced needle valves and seats. Set accelerator pump to middle notch – less aggressive, rich and used a slightly less aggressive step up spring – pink. Floats look okay, no sloshing fuel in them. My main jets are 401, secondary 401 and metering rods 7047. No change from before. I did find some debris in one of the float bowls that I initially thought was the cause. But after the carb rebuild and still having the problem, I think might have just been flakes from the gasket when I separated the halves.

Fuel pump. Has good voltage, 13+ when engine is running. Can hear the pump running with a sound dowel stuck in my ear. Don’t have a pressure gauge – yet.

Fuel/Water Separator – Opened this up and it looks clean. Have had this problem on several different tanks of gas, so I doubt fuel is the problem.

Plugs – pulled them all, look good, no cracks in insulation. . Slight tan color, no carbon on electrodes. Connected each plug to a timing light and observed the light at idle and 2000 RPM. No difference in any of the plugs. Pulled each plug off one at a time when at idle and engine ran rougher for each plug pulled.

Timing – Timing looked steady at idle and advanced some when at 2000 RPM. Don’t have any marks or timing tape for the balancer.

Distributor – pulled the cap, looks okay. Pulled the wire from the coil, also looks okay. Checked for 12 volts to the coil and from the ignition module. 13+ when engine is running.

Coil – used a voltmeter to check for opens, shorts per some diagnostic info I found from a Seloc Mercruiser repair manual. Checked out okay.

Not sure what my next step is. Throw new parts at it, get better test equipment or find someone with the proper diagnostic tools to take a look at it.
 
Float level? no mention of it above...may want to lower the fuel level 1/8" and see what happens.
Timing - you need to verify full advance at the proper RPM and to ensure it is steady (stable) for any given rpm.
Plug wires - if resistance type and more than 5 years old, you may want to change them...I seen more than a few with the failure only existed when the boat was running down the river - no issues at all tied up to the pier.
Coil - may only fail when under heavy load (pulling a skier) - some would say they only fail when hot.

I wouldn't throw parts at it until their need is clear...maybe just an improvement (or expansion) of the diagnostic procedures you are using...this is the stuff that separates the men from the boys. Believe me, once you find the gremblin, it will all seem Obvious!!
 
Thanks, I forgot to mention that checked the float adjustment.

I found another test mentioned in the Seloc Mercruiser repair manual that describes how to test the pickup coil. Also mentions how to test the resistance of the spark plug wires - says they should be about 7,000 ohms per foot. The spark plug wire set is 2 years old.

Electronics - like the coil tend to fail more under heat. My problem is the reverse, after about 10 minutes of running, it tends to improve.

I'll try to see if I can improve on testing the timing. See if there are timing marks on pulley or timing tab on the block. The Seloc manual doesn't have a lot of specifics on how to measure the appropriate advance at different settings. Looks like at idle it should be 12 - 15 degrees BTDC and at 2600 RPM, 23 - 25 degrees BTDC.
 
I've found that shaking the plug leads, with the ohm meter connected, is a much better test...also, the 7000 ohm/foot value is nominal...I've seen 4000-8000 ohms/foot.

The electronics may not be improving their performance when warmed up...it may be fuel condition that is mitigated with the heat.

For the timing, you can buy a timing tape (measure the OD of the balancer before you buy) or you can mark the balancer and just use the zero on the tab. If you have access to one, an advance timing light offers a faster solution with less effort...just make sure you use an accurate one.
 
Thanks.

I tested the spark plug wire set anf got the following results
1 16.4 ohms
3 15.4 ohms
5 15.6 ohms
7 12.6 ohms
2 18.0 ohms
4 15.6 ohms
6 13.8 ohms
8 12.6 ohms
coil 7.2 ohms

Since the lower number plugs have longer wires, this looks okay. I'll look at the pickup coil and timing again tomorrow.
 
Ran the engine today. Choke fully opened as it had before. Tried to force it shut but it's solid in the open position, so I really doubt it's closing during skiing. Also checked the timing. There's a single timing marks on the balancer and just a simple v grove on the engine. Seems to advance smoothly as the RPM increases. Does seem more advanced then 8 degrees at idle but offset as it advances seems correct. But distributor is tight so if it was more advanced at idle, this wouldn't be a new problem.

Found a service guy that has better test equipment, so I'm bringing the boat there now. Will post updates as I get them but probably wouldn't hear anything until next week.
 
Got the boat a couple of days ago and it looks the the ignition control module was intermittently failing. The service guy had a better timing light and could see that the advance was moving around independent of the throttle. Before it would loop at idle and that is now fixed. I need to test it under load and can't get out to the course until next Monday at the earliest.
 
Thanks, guess I wasn't clear enough. The advance has been set correctly and verified while the boat was in the shop. So that's one problem fixed. Now I need to run the boat under load to make sure that was the only problem I had.
 
Bummer, but the problem persists. The idle is steady. Pulling the skier out of the water, then engine stumbles until it gets to above 2000 RPM, then smooths out but lacks power. Talked with the service guy and he wants to do a test on a lake since he can't put a load on it out of water.
 
I went back and checked your calibration...seems richer than stock but the power valve/stepup spring change is not what I would call aggressive but rather rich. Seems to me the carb is givng your small block way more gas than needed. The factory calibration feeds enough fuel to keep a big block happy...if you have an unmodified small block, there's really no need to add more fuel thru a rich cal.

If you really want to optimize the tuning of that engine for your application, you may want to consider getting a decent mallory marine unit...that will let you tailor the spark advance vs being 'stuck' with the curve in the EST module.

Wondering if your initial calibration was 'masking' some other issue that you have since fixed...hard to tell...

Maybe you want to see what the service guy says and then re-evaluate your situation...either way, might consider keeping more complete notes of the changes you make and it may keep you from running in a circle in the future.
 
Thanks, richer is probably a better term. For competitive skiing you want a a very quick and defined throttle response, so I used the term aggressive. When I first got the engine, it was doggy. Not much power coming out of the hole and slow to respond to throttle movements in the course. Perfectpass, an automated RPM control, would keep increasing the throttle trying to maintain a target RPM. Eventually the engine would respond and surge 80 - 100 RPM, unusable for skiing. RPM adjustments of +/- 10 are more normal. Eventually, I decided to tune the stock Edelbrock. I initially went to the richest configuration available with the Jet kit 1488 using both jets, step up springs, metering rods and accelerator pump settings. This solved my problem. Thinking I was running way richer then I needed, I backed off to 1 stage richer than stock. Problem still solved, engine responsive in course. That was 2 years ago and engine ran fine until the recent problem.

As to masking an earlier problem, that's possible. But something broke recently and that's when I tried to fix things. I'm going to take a closer look at the coil. I'm wondering if the RPM pickup for the tach or Perfectpass could be causing me a problem. It's a 2 hour round trip to the lake to do load testing and that's the only way to reproduce the problem.
 
Tachs have been the causes of many ignition issues...typically it is more of a won't run case..easy enough to just disconnect the wire for it, at the coil. I've found a 'doggy' or flat response is typical for a rich condition.

ski boats are typically "light" for their length and many push them with small blocks. I'd be inclined to measure the vacuum during use and pick the spring from there. I'd also be inclined to gradually try leaning things out in the calibration...you have to be careful with a marine ap as you don't usually get a second chance with detonation. You can also use the vacuum gauge to help with the calibration.

Finally, you have to make sure the rest of the engine is fully functional when dialing in the carb jetting...if not, you get to repeat it again.
 
Finally got a chance to look at engine again. I've ordered a new coil and pickup coil. Coil testing didn't point to any problem. On my pickup coil, I got resistance to ground when manual says it should infinite. Not sure how to remove pickup coil, couldn't see retainer that manual mentioned. Maybe when I get the replacement, I'll have a better idea.
 
Well, it's finally warm enough to get back skiing and it looks like I've finally solved my problem. What I did was replace the coil, rotor, cap, plugs and plug wires. When I installed the plug wires, I made sure they were twisted to prevent any cross ignition. I decided to throw parts at the problem since a step by step process of replacing a part and doing a 2 hour round trip to test could likely have been a more expensive option and certainly more frustrating. While I'm not sure what exactly caused my problem, I suspect it was the coil since it was an intermittent failure that improved after about 15 minutes of operation.

Thanks all for the comments.
 
Glad you got it figured out and that you were kind enough to post "the rest of the story"...if you keep a log book, make sure to add a similar entry so the next time it happens, you'll know where to start....
 
one thing that you did not talk about.....is a fuel regulator. INSTALL ONE !! and install a small inliline fuel guage. your float adjustment will do you no good when you are hitting waves, and are on a constant changing plane. an electric fuel pump will tale every advantage of every little variation of the float level. set the fuel pressure at @ 5 psi while sitting at the dock running....NOT in your driveway. if your top end is ok....leave it at 5. if it starts cutting out, increase it to 6 psi.....and thats it. it is to your advantage to see if you can run at 5 psi at first.
 
Makomark - yeah, it pisses me off that an interesting post to your problem just ends with no results. Like reading a joke but leaving off the punch line. You know the problem was resolved and it sure would be helpful to others to know how the problem was resolved. l've gotten way more help from forums than I've contributed, so when I get a chance, I want to help out.

Crankbait - interesting comment. I use my boat on a waterski lake, so waves don't exist. There is a slight change in plane for a tournament ski boat coming out of the hole but not much. And skiing the course, the water is glass flat. But I could see how this could be a problem in ocean going boats.
 
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