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Weak fuel pump?


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On 10/25/2021 at 9:54 PM, cimmer said:

When you say the smaller of the two holes, are you aware there are 3 holes between the engine and the throttle blade. The smallest of the holes is the idle Pilot outlet hole for the idle circuit.  This hole is passing a fuel/air mixture and if the black stuff is coming out of there, it could be a bad o-ring that is used in the pilot screw set. The other 2 holes appear to be air holes for vacuum the coasting enrichment valve assemble and piston valve/diaphragms.  You might have to remove the pilot screw and see what shape the o-rings are in. Be aware there is a spring, washer and o-ring in there and they can be hard to remove. You might need to stick a small stiff wire in there to work them all out and there are replacements available for a number of sources.

Hope this helps.

Rick F.

 

You are right, I missed the third hole until I shot some carb cleaner in the mating hole that the pilot jet lines up with from the jet block. 

I went ahead and sent the carbs out to Mike Eykamp in hopes that he will find out what I have been missing. Since I haven't been performing a true carb tear down and rebuild then the issue is probably with my halfassed attemps at focusing on the fuel part of the carb only. 

I did take out the fuel sender and looked into the tank, doesn't look too bad for a +30 year old bike in my opinion. Nothing I can see that would explain the carb getting gummed up after several hundred miles.

I plan on replacing the fuel lines and pump again just to be sure.

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  • 4 weeks later...
On 11/21/2021 at 11:04 AM, videoarizona said:

Agreed. Tank needs to be cleaned and sealed. That rust will flake off... Hopeful be caught be filter. What doesn't get caught will cause carb issues.

You have put a lot of effort into the scoot... pleas keep going. Once done, the bike will be a joy for years to come!!

I have to admit, I have thought about selling this thing know than once over the past couple of months. Hopefully I will be able to get this figured out and fixed this time around.

I got my carbs back from Mike and want to make sure everything is okay. I've got a new fuel pump and lines as well as filters.

If I'm going to do the tank, does anyone know what's involved to remove it? I had heard you basically have to split the rear frame off but correct me if this is wrong. I hadn't thought about removing the tank and relining it as my 82 Honda is way worse and I haven't been having any similar issues as what I'm having here. Also, my screens in the tank and fuel filters are perfectly clean with no hint of rust discoloration.

Did these tanks have any sort of liner applied at the factory? This tank has some rust but I don't see any evidence of a liner ever being there in the first place, unless it has dissolved over the years. I would think there would be flakes of debris other than rust in the tank if that were the case but can't see anything so far.

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The tank on my 85ZN700 is rusty.  When I bought it in 2009 with 1k miles on it, I sloshed the gas around and dumped it to get the rust particles out and put a filter in the line and I've never had a problem as far as I know with rust clogging up the carbs.  They will clog up easily if it sits for a while but with a 700cc engine with 4 carbs the passages are really tiny and it doesn't take much sludge to plug something.  I keep Gumout with PEA in the gas which helps this issue.  My 2 cents.

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On 8/5/2021 at 8:41 AM, videoarizona said:

Glad to see things are coming together! 

Regarding mpgs, the best for economy comes when you let the motor run. IE,  don't bog her down at lower rpms. Especially riding 2 up. Staying in a lower gear, running 3k to 4k rpm, will give you better mpgs than shifting up. Seriously. Experiment. 

Change oil regularly, change plugs yearly and let her run!

Change plugs yearly? How often on wires?  I’ve been going through my own woes and last I rode her a month ago things were great.  I’ve been wanting to get out just haven’t.

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18 hours ago, Pasta Burner said:

Change plugs yearly? How often on wires?  I’ve been going through my own woes and last I rode her a month ago things were great.  I’ve been wanting to get out just haven’t.

I have the Ignitech box on this with cop's instead of the factory coils and wires. I do have a new set of spark plugs I'm going to be installing soon just in case. Don't think that is the problem but we'll see. Strange how I can blow out the jets and passages and it runs like a dream for awhile then happens again. Filters look as clean as when I installed them. One installed between the tank and pump and the other between the pump and carbs.

Mike said that the carb floats were set to the wrong height, too high. Also said the wrong metering needles were installed. Not sure if that would cause my problems but glad to have it back to the right settings I think.

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18 hours ago, TTrax said:

I have the Ignitech box on this with cop's instead of the factory coils and wires. I do have a new set of spark plugs I'm going to be installing soon just in case. Don't think that is the problem but we'll see. Strange how I can blow out the jets and passages and it runs like a dream for awhile then happens again. Filters look as clean as when I installed them. One installed between the tank and pump and the other between the pump and carbs.

Mike said that the carb floats were set to the wrong height, too high. Also said the wrong metering needles were installed. Not sure if that would cause my problems but glad to have it back to the right settings I think.

The fuel line between the filter and the carb could be deteriorating on the inside

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That was my problem on my 1st gen. Constant issues with carbs and running until I replaced that fuel line. 

Plugs at least every two years. Wires last a while unless you live by the ocean. Salt corrosion can occur without being seen inside plug wire connections. 

2gen coils and wires seem to be less of an issue than 1st gens that are separate.

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8 hours ago, saddlebum said:

The fuel line between the filter and the carb could be deteriorating on the inside

I would like to think not since it was brand new Gates hose installed a couple of months ago.

Regardless, I will be changing them again asking with another fuel pump just to be sure. Planning on at least cleaning the tank if not removing it and derusting it before sending fuel to the carbs.

I appreciate everyone's thoughts and suggestions on this and hope to have it back to road tripping this next riding season!

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  • 4 weeks later...

OK just a quick update, still working on this issue. Slowly but surely. I did notice something strange but maybe of no consequence but figured it would be worth noting.

The first photo I had shared awhile back. It didn't mention anything about it as it looked to me as if someone had applied a lot of sealant quite sloppily between the petcock and the tank. I didn't think more about it until I had dried out the tank with a heater and blew it our with compressed air. The next picture was after blowing out the tank, and the last was after blowing it out specifically in the area of the petcock. What I thought was orange sealant seems to have been rust but of a bright orange color which I haven't commonly come across. Possibly rust in the presence of water? I'm not sure, also not sure if this was causing my problem or not. Seems like rust would have stained the fuel filters and the fuel bowls of the carbs but I can't say I know for sure. The filters and bowl are clean for the most part.

For now there are no loose rust particles in the tank. I have considered removing the tank but not sure how much it would take to get it out. Looks like it would be a lot of work but might be worth it in the long run. I might see if there is anyone local that would perform a rust removal and nickel coat a tank if possible. I have heard horror stories of people using a tank liner and having it flake off and plug up fuel filters, so I am hesitant to do it unless it is absolutely necessary.

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  • 2 weeks later...

Just a quick update... decided to go ahead and drag myself out to the garage today and decide how I wanted to proceed. After much looking at the bike and trying to see how much work it was going to take to get the tank out, I started taking it apart in earnest. It wasn't as bad as I thought it was going to be. I took the luggage cases off the bike, took out the air system, and unplugged any wiring harness connectors I needed to so I could get the frame off the back of the bike. I did find the top left frame bolt was missing so that was concerning for sure. Now just to see if I have someone relatively local that cleans out tanks and treats them, or decide if I want to try to do this on my own. Pardon the mess in the garage, I didn't get it properly cleaned out and took these photos before putting up my tools that were strewn about the work area, along with leaves that had blown in yesterday when loading up some stuff.

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  • 4 months later...

OK, it's been awhile since I had updated my progress... mostly because there hasn't been much progress.

I did finally do some research into cleaning the rust out of the fuel tank. I had bought a tank liner kit (Kreem), but after reading a lot of negative reviews, I decided I would forgo doing it for now.

I finally decided to go with muriatic acid. After using a gallon undiluted, I made sure to agitate the tank around off and on for about 2 hours. Afterwards I neutralized and rinsed with water and baking soda. After I got most of the water out of the tank, I poured some alcohol in the tank and drained it too so I could get most all of the water out as possible. That was followed up with a leaf blower in the opening for the fuel sender for about 10 minutes. Finally, I followed up with a good coating of WD-40 and drained the excess out.

Hopefully this will last for awhile, now to start getting it put back together again. The weather here is already nice and been driving me nuts listening to everyone driving around on their bikes. At least I still have the trusty old CB750 to ride around on but its just not the same. Hopefully this does the trick, my wife has already said if it doesn't its probably time to get rid of the Venture. 

I attached some before and after pictures, so far it looks like it did a decent job.

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  • 2 weeks later...

Well I just got back from a ride after syncing the carbs, runs great so far. I will need to put the bodywork back on, Only time will tell if it is really fixed. Usually it runs great for a few hundred miles after taking the carbs apart and cleaning them. I will try to provide an update if I get over 500 miles with no issues. Really hoping for a good outcome because I am tired of tearing this thing apart.

The only issues I can think of that might have been happening is the sealant I used to install the fitting on the fuel pump and the previous owners use of orange RTV to seal the petcock to the tank. When I took the old pump apart for inspection, I removed the fitting and some of the sealant I had used broke off in a piece. I sprayed some carb cleaner with acetone on it and it dissolved in a matter of seconds. Also, when removing the orange RTV on the petcock, it was difficult to remove. I sprayed some of the same carb cleaner on the RTV and while it didn't dissolve immediately, it sure let go of the metal pretty quick. Hoping this is what was causing the issue because I have eliminated both of those sources now.

Thanks again for all the suggestions and encouragement so far. Hopefully this will be the end of the problems but I will let you all know either way.

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So far, nothing new to report. I had tried to take it out for some significant riding this weekend but the weather hasn't been cooperating since. I drove about 35 miles on Friday and a little over 60 miles on Sunday. My wife got cold during the ride so we turned around and came back. I have been obsessing over any little irregularity and trying to determine if the engine is running worse or the same as it was when I put it all back together again. So far the engine running hasn't changed since I put the carbs back on, but I don't think I have enough mileage under my belt to start to relax yet. The weather this weekend is supposed to be better so will be putting some more miles on it at this time.

I'm trying to mentally prepare for the possibility of the issue coming back, but I can't really think of much else that could cause the problem. The tank has been acid washed and the fuel system between the tank and carbs has been completely replaced (new fuel lines, new fuel pump, filter before and after the pump).

One thing I am checking for is other possible places that fuel interfaces with the carbs other than the obvious places such as the fuel jets and enrichment circuit. I am looking at the service manual diagram of the carbs but don't see where the fuel from the enrichment circuit is released into the intake. Does it go to the pilot jet hole in the carb body or some other place? Also am wondering if it is possible fuel can get into the area where the adjustment screw for the air adjustment is?

Hopefully I am just being overly cautious and the problem won't come back. I am just trying to get a plan going in case it does. I don't think that the air adjustment has ever been touched as the plugs are still in place.

Just for reference, I am attaching a short video of it running. Idle is a little lumpy but has been that way for as long as I have owned the bike. Not sure if this is common or not, but as long as it doesn't change drastically I am fine with it.

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I would say just go out and ride it and enjoy..  get about 1,000 miles on it and then maybe bring it back and check the pilot screws for the idle mixture and then resync the carbs if needed.  One thing I do is when I fill my gas tank, I usually add some seafoam to the gas to help keep it fresh and to help keep the fuel system clean.  About the only time I dont add seafoam is when I am going to be riding all day and filling the tank a few times, then I usually wait till the last refuel before adding it again.

Rick F.

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