surging problem
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=3381
Printed Date: November-23-2024 at 8:54am
Topic: surging problem
Posted By: jimbo
Subject: surging problem
Date Posted: April-17-2006 at 11:30am
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I'm having a problem with surging after the engine gets warmed up when running above 3500 rpm. I replaced the fuel filter and the fuel pump but I'm still having the same problem. It runs fine at 3K rpm but above 3500 it's like I'm gooseing the throttle. It also doesn't have the hole shoot it used to.
Any help? |
Replies:
Posted By: Nautique2001
Date Posted: April-17-2006 at 12:11pm
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My issue at one point with a high speed skipping or lose of power was my timing. I had a Prestolite electronic ingition system installed and also sprayed WD-40 on the timing advance springs in the distributer. The problem immediately went away. Good luck
Ken ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1052&sort=&pagenum=4&yrstart=1986&yrend=1990" rel="nofollow - Nautique 2001 |
Posted By: skyhawkflyer
Date Posted: April-17-2006 at 3:10pm
| Check your fuel pump pressure, it may be a cracked diaphram in the pump. |
Posted By: Jim_In_Houston
Date Posted: April-17-2006 at 3:57pm
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Jimbo. The key may be "after the engine gets hot". Does it run fine when cool or normal? Is the engine overheating? What kind of engine/carb setup are you running?
And to confirm, your "holeshot" is noticibly less? ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: jimbo
Date Posted: April-17-2006 at 5:26pm
The hole shot is noticably poorer -- takes longer to get on plane. What I mean by when it's hot is when it's been running a while. The engine isn't overheating. I'm going to take it out this evening and see when the surging starts. The engine is an '83 351W Commander. It has Holley 4160 carb. I'll check the timeing this evening also. I converted to Electronic Ignition about 2 yrs ago. The fuel pump is new. For now I'm going to assume that's not the problem. What about problems with the carb? |
Jim_In_Houston wrote:Posted By: David F
Date Posted: April-17-2006 at 5:34pm
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My vote is electrical. Check for loose wires (at key, coil, connectors plugs, etc.). Swap in a known good coil. Suspect the ignition module. Disconnect the tachometer to take it out of the equation.
let us know what you find. |
Posted By: jimbo
Date Posted: April-17-2006 at 7:26pm
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Ok, it's definitely a fuel flow problem. It ran fine for 20 mins or so then it started cutting out again. Temp was always 140-160. When it started to surge, I checked the fuel pressure before the carb and it was zero. This rules out a problem in the electricals, right?
I checked the timming and it was fine. 10 BTC at idle. 30 BTC at 3000 rpms. I sprayed some WD-40 on the springs and weights for good measure. I also sparyed some carb cleaner in the carb. LOL I was running out of things to do. I'm still going to assume the new fuel pump is fine. Any other thoughts? |
Posted By: 81nautique
Date Posted: April-17-2006 at 8:44pm
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A little out of my league here but how about a clogged fuel filter.
------------- You can’t change the wind but you can adjust your sails |
Posted By: bkhallpass
Date Posted: April-17-2006 at 8:52pm
How about a larger hampster?  BKH------------- Livin' the Dream |
Posted By: JEFF KOSTIS
Date Posted: April-17-2006 at 9:14pm
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Assuming it started before the fuel pump was replaced???
Jeff... ------------- MUSTANG COUNTRY http://www.correctcraftfan.com/diaries/details.asp?ID=1074 - 1974 Mustang 17 http://www.correctcraftfan.com/diaries/details.asp?ID=1093 - 1976 Mustang 17 |
Posted By: jimbo
Date Posted: April-17-2006 at 10:16pm
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Yes, the problem started a few months ago. I replaced the fuel filter and the fuel pump but that didn't fix the problem.
Let me give a little more detail about how I'm measuring the fuel pressure. When these problems started, I bought a small, in-line gauge that's connected to the fuel line about 10 inches before the carb. This way I can see the pressure is at 7 psi while it's running fine and that it drops to 0-2 psi when it surges. If I back off the throttle, the pressure comes back up. (Maybe I'll remove he gauge to be sure it's not the problem.) Right now I'm thinking it might be something like: 1. Something with the carb, which I know very little about. I can't see how that would cause pressure to drop though. 2. Air getting into the fuel line between the tank and the fuel pump. 3. Something in the tank obstructing the flow--like a hampster 
I'm ruling out electrical problems based on the drop in pressure. Same for the high voltage stuff-- coil, distributor, plug wires. I'm still trusting the new fuel pump to be good. Can anybody think of anything else? Come on, don't be shy! |
Posted By: GottaSki
Date Posted: April-17-2006 at 10:31pm
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SOme boats (read brands, like ski centurians) had an additional cone screen, sandwiched within the elbow fitting and the dip-tube in the tank. the fittings have to be disassembled then throw the screen away.
The symtoms were uncanningly similar - good for one run then falls flat and surges. Also check if the fuel line from the tank is not getting soft, punky and collapsing. Beware, the lean condition can frag a piston or valve or both. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: Jim_In_Houston
Date Posted: April-17-2006 at 11:23pm
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Could your gas tank vent be clogged? I have heard of a dirt dobber (a type of wasp that builds its house out of mud) making a home in a gas tank vent. ------------- Happy owner of a '66 and a '68 Mustang |
Posted By: 64 Skier
Date Posted: April-18-2006 at 5:10am
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If you have not removed your tank and cleaned now would be a good time. I assume the fuel gauge was working properly and if indeed the fuel pump is new and working properly the only idea I can think of is the tank or fuel line is clogged. I had a car do exactly this...tank was full of rust making the engine surge. Both tanks on my old boats were the same and cleaning them was one of the first "projects" done. Both had the little screen on the inlet inside the tank. Both screens were 70% clogged as well as debris in the elbow. Also check under your tank for rust. The '64 was almost rusted completely through so we fiberglassed it.
The reason to make sure the tank is sound is twofold...first is safety and second being it's hard to troubleshoot what you can't see. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: David F
Date Posted: April-18-2006 at 8:54am
| Does it happen at higher engine speeds only. It could be that you are sucking in air somewhere along the suction side of the fuel pump. For instance at the fuel filter clamps. |
Posted By: tcarden
Date Posted: April-18-2006 at 3:11pm
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What about the anti siphon valve? ------------- "Boat - A hole in the water surrounded by wood (and fiberglass) into which one pours money" |
Posted By: jimbo
Date Posted: April-18-2006 at 8:41pm
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Thanks everyone. I replaced the fuel line from the tank to the filter when I replaced the fuel gauge sending unit a while back. Maybe I knock some junk loose in the tank then.
I need to pull the boat out this weekend and change the fuilds. I'll pull the elbow and check for junk then. Jim and tcarden: your point is well taken on the vent. There are some mud-dobber nests on the boat dock. That vent is a nice cozy space where they would build a nest. I'll post what I find. |
Posted By: WakeSlayer
Date Posted: April-19-2006 at 6:01pm
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I had a 90 SN and had the stem break off the top, in side the tank. As I recall, it ran poorly for a couple days, then died on the lake one day. After changing the filter, water remover, etc, I decided to pull the tank. As I was removing the (I believe) sending asm at the top, I heard the stem fall into the tank. I replaced with a newer plastic one so I did not have to completely pull the tank. Wierd problem, no idea how it happened, the boat was only 7 years old at the time. Good luck. ------------- Mike N 1968 Mustang |
Posted By: jimbo
Date Posted: April-21-2006 at 1:33am
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I cruised for about three hours this evening at idle just drinking and chatting (and getting rid of that expensive fuel). No issues. I'm sure it's something getting sucked down in the tank at high fuel flow. (Maybe it's the float on my new sending unit ?!?!?!?!) I'm pulling it out this weekend for a tank drain and cleaning and oil, fliter and transmission fluid change.
Update on Sunday. |
Posted By: jimbo
Date Posted: April-25-2006 at 12:56am
Well, I pulled the boat out over the weekend and changed the oil and transmission fluid. I pulled the ahh, how do you say, syphon, tube from the fuel tank and sprayed carb cleaner down it. The liquid came out kinda brown so I took the tube apart and there was a screen filter inside that trapped some gunk. I cleaned it out and reassembled with good Teflon tape (the gasoline resistant kind). I hope that was the problem. In the mean time, I started washing and compounding and waxing the beaut. I'm hoping to drop her back in Wed or so and see it the screen cleaning took care of things.
Also, the pulley on the boat lift motor broke so I need to get a new one before I put her back in. It's always something 
I guess it could be worse; I could be living in an apartment in some God foresaken part of the world with no boat and no water in sight! |
Posted By: bkhallpass
Date Posted: April-25-2006 at 1:13am
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You got that right Jim. It's all good. BKH ------------- Livin' the Dream |
Posted By: jimbo
Date Posted: April-27-2006 at 1:37am
Yahoooo!!! I'm Back! GottaSki gets the prize:
She's running like a champ again. Except for the transmission fluid leak problem. A new thread to follow. |
Posted By: GottaSki
Date Posted: April-27-2006 at 4:55pm
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Good to hear, happy for you! ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |