DrMacDaddy's Poor Fuel Mileage Thread

If it is domestic, have more. Be carefull with the Canadian amber.

 

Post-Winter Update to DrMacDaddy's VFR750 Suffering Poor Gas Mileage

Now that the cold, snowy Winter weather has moved on in the Kansas City area (except for today that is), I decided it was time to get the VFR out of the garage and fire that bad boy up. Here's an update to my bad gas mileage saga. Those reading may want to grab a cold beer,.....and some tissues to wipe away the ensuing tears that will no doubt roll down your cheeks. Having followed up on any and all suggestions made by those members following my thread, and the few other threads out there concerning poor gas mileage,.....I decided to replicate a technique provided to me from one of our fellow VFRWorld warriors. This technique for power cleaning out the inside of the carbs is as follows:

The forum member had suggested using Sea Foam as a gas-additive cleaner....and told me about a setup he used to power clean the inside of his carbs. Basically, he just removed the tank, and then connected a large funnel w/ attached gas hose. He then used adapters to connect this setup to the gas hose that connects to the bottom of the tank. With this setup, the tank is gone....but he could run straight gas or any mixture of gas and cleaner in the funnel....and then startup the bike and run it for 15-20 mins. Then he put in straight gas and ran for another 20 mins to flush out the Sea Foam. At that point, the funnel setup was removed and the tank reinstalled....and then out on the road for a 30 min ride at high rpms. He said it worked like a charm. Initially, the exhaust pipe expelled a lot of blackish smoke as he tooled down the road, and idled a little rough. However, after 15 mins on the road....the exhaust stream cleaned up, and the bike idled smoothly again. His mileage then rose up to a respectful 40-45 mpg.

I tried to replicate his setup w/ supplies from the local Ace Hardware. I removed the tank and connected the funnel/gas hose in it's place. I mixed up a 50/50 mix of gas and Sea Foam....and then started up the bike. It ran fine for about 15 mins. Most of that running time was at idle speed, but here and there I would raise the engine speed up to around 3K for a few seconds...and then back down to idle speed. I also revved up the engine several times. Around 20 mins into this scenario, the engine just sputtered and died. Since the funnel was almost empty, I figured it was just a lack of pressure since it was an open system with maybe an inch of gas at the bottom of the funnel. I emptied the 50/50 mix from the funnel, and replaced it w/ 100% gas. Then I tried countless times to fire the bike back up so that I could at least flush out the Sea Foam that was still inside the carbs. However, the engine just wouldn't start again. It was almost December, so I wrapped everything up tight to keep debris out of the tank and gas hose. I also put a battery tender on the battery, trickling power in over the Winter months to keep it fully charged and fresh.

Two days ago I hooked the tank back up, and tried to fire up the bike. Nothing. I tried and tried and tried,....but it just wouldn't start. Usually when you try to start a bike that many times, you end up flooding the carbs....but it had no smell of excess gas at all. So, my guess is that the carbs are not getting any fuel at all....or at least not enough to fire up the engine. Not really sure what to do at this point in time. Maybe the carbs are literally gummed shut inside, and that's why they can't get enough fuel to startup the bike. The engine turns over without issue, and the battery is new. The plugs are all getting adequate spark, so ignition system is okay. It's my understanding that the fuel filter is actually inside the gas tank...mounted to the very top of the fuel petcock assembly that inserts up into the tank from the bottom. Perhaps the fuel filter is fully plugged. I checked all the obvious things,...such as fuel valve was in "On" position. The Run/Stop switch was in the Run position. The bike was in neutral, and I even sat on the bike with the side stand up to ensure that wasn't the problem. All those were ok. In looking at the service manual for 90-93, I was never able to see exactly where the fuel pump was located. Suggestions as to where to look for that? Any ideas at all on what I can try to get the bike to at least fire up again.....before I end up pulling the carb assembly for professional cleaning? Another idea that's actually cheaper is to buy a complete carb assembly off of Ebay. I found one from a 93 that only had 5275 miles on it. The assembly looks in great condition, and very clean. Price tag is around $195 plus $30 S/H. That's definitely cheaper then having the carbs disassembled and cleaned. I'm open to trying anything that you all can come up with. At this point, I having nothing to loose....and everything to gain. Thanks everyone for your dedicated input. Ron

 

I don't think there is any quick and easy way around this. You are going to have to remove the carbs and tear them down to find the issue. To go out and buy the e-bay carbs is a huge gamble. Who knows how long they have been sitting and the clean exterior is no guarantee that the interiors are just as nice. More than likely, the o-rings and gaskets will be all dried out and need replacement just like your current set of carbs.

So the way I see it, you have two choices,

1. pull the carbs and give them to someone to sort out
2. Pull the carbs and tear them down yourself with our group of technical experts watching via the internet (over your shoulder)

 

Where is Toe and Squrilleman? Aren't they Carb expert

 

They are busy upgrading their bikes to fuel injection! otstir:


BTW, that is one sweet looking 93 ya have there DrMacDaddy!

 

Your Sea Foam experiment likely just knocked something loose and clogged up the idle jets. However base on what you are describing I would not be a bit surprised to find that the needle and mains were either clogged or damaged or had bad seals to begin with. If you aren't familiar with carbs don't let that scare you off from methodical inspection and repair. I'm sure you can get a wealth of info here and elsewhere. You may be looking at a simple cleaning or seal and o-rings and jet replacement. Along with carbs I would also look at intake related vacuum leaks. I'm betting it's a two fold problem based on the info you've provided. None of it has to necessarily be expensive however.

 

Yep, you really need to pull the carbs and take a look inside. You are not going to find anything on speculation. That jumble of stuff that makes up the carburetors on a VFR can be pretty intimidating but take it one step at a time, go slow and be careful. There are just four individual carbs so you can take them one at a time.

 

Maybe an intermittent problem with fuel pump or its relay ?? Just one leaky float needle will make for running/starting problems. I suggest that you open each carb drain screw to see it they're getting fuel. If you leave one screw open while you crank the engine you should see new drippages emerging if fuel system is working right.

If your vision problems make close-up work difficult, you have my offer to go through your carbs with a thorough inspection and cleaning. PM me if interested, but please make sure you have no problems with sparks or bad plugs first.

 

^^^^ This is a good idea, and should be the first thing you check. When you turn the screw fuel should drain out of the appropriate "nipple" on the carb bowl. Just be sure you're turning the Drain screw and not the Pilot Screw.

Also pull your plugs and see if they're wet.

Getting a new fuel filter won't hurt either. I wouldn't be surprised if the Seafoam sitting in it all winter ate it up.

Seafoam is a great product. It just needs to be used sparringly and carefully.

Keep us updated OP....and don't give up. We're behind you.

 

Slowbird,.....was I right about the location of the fuel filter being inside the tank at the top of the fuel petcock assembly? Pulling the tank again will not be a problem for me. As with anything, once you've done it once.....2nd time around goes much faster. Jethro911.....thanks for your input and for the compliment on the bike. It might be for sale soon!!! :crazy: BigJim_59.....Squirrelman.....Scubalong & Shmerick.....I will keep your comments in mind as I jump in today following up on your leads. As an IT Tech guy, I've always recognized the power of specific forums....but the members of VFRWorld are truly in a class of their own. I can't believe the support I've gotten from you all. I'll start with checking the drainage of each carb and examining the condition of the 4 plugs. I did pull the backside 2 plugs in Nov of last year, and they were a little sooted, but not too bad. Obviously as sign, though, that the upper cylinders were getting blasted with fuel/air mixtures that were a little on the rich side. Key is to be rich in the bank, and not in the carbs,..right? As far as pulling the carbs,....going thru them thoroughly and cleaning them methodically,....then reassembling them and remounted the carb assembly............what's the worst that could happen?......My bike might not start??? Ha ha ha ha. Ok,....deep sigh,....cracking back and knuckles,.....saying a few choice words to the Big Guy in the Sky,.....and jumping in. I feel like I'm heading to the hotel on my honeymoon night. I'm excited, but my hands are shaking.

 

I dunnoh where it is exactly on the 3rd gen. On the 4th it's on the side of the bike under the plastics. Small roundish whiteish plastic cylinder with an arrow on it.

Come to think of it, the Fuel Filter was the same and in the same spot on my 2nd gen so it might be on yours aswell

 

It's not that bad. It just looks bad because all for carbs are linked then jammed together. Take your time. Do one at a time. Check everything and I mean EVERYTHING. When you think you have done with that carb and are ready to button it up check it again. The worst part about cleaning and checking carbs on a VFR is having to do it over again.

 

Well.....once I removed the tank, I decided to hook my funnel/gas-hose setup back inline with the bike's fuel hose....and this time fill the funnel up with 100% gas (no Sea Foam). My biggest worry was the 50-50 mixture sitting in the carbs over the Winter. It took about 8 attempts to fire it up...and it died after a few seconds similar to last Nov-Dec. This happened over and over. However, I just kept trying....and eventually I got it to fire up and keep running. Lots of white smoke out the pipe.....sputtering and coughing.....but after 2-3 mins it finally picked up speed and began to run more smoothly. After 5 mins, it ran normally with choke fully disengaged. I ran it until the fan kicked in. Here are a few pics of my setup:

View attachment 22362 View attachment 22363 View attachment 22364 View attachment 22365

My only concern in the beginning.....was some white smoke that I saw rising from somewhere behind and below the rear cylinders. My first reaction was burning/melting electrical wiring, so I quickly shut the bike off. After several mins of cooling, I started it again, & smoke appeared again after a few mins. I repeated this several times until I located the source of the smoke. From my perspective, the smoke seems to be coming from a section of the exhaust pipe where 2 sections are bolted together underneath the right side of the bike's frame. I took several short vids with my cell phone, but the smoke is difficult to see in the vids. I did not notice this smoke last Winter, when I used the same funnel setup while cleaning out the carbs. I'll try removing the plastics on the right side, and see if I can get a rachet-socket in there to tighten the 2 bolts holding those pipe sections together. Hopefully that will stop the visible smoke.

 

Once the abundance of Sea foam is burnt out of the engine, the smoke should stop. There is obviously a small leak at that slip joint.

 

Awhile back, when KennyBobby first transferred my request for help to a new thread,.....someone mentioned checking the scent of the dipstick for the possibility of gas in the crankcase oil. At that point in time, I checked the dipstick and did NOT feel like I could smell gas. However, it has been on my mind a lot lately, so I decided to revisit that chance last night with my wife and son by my side. WIth the bike level, I had both of them smell the dipstick,...and both of them said that they COULD smell gas. Next, I had them both put their nose close to both the dipstick's hole in the engine's casing as well as the larger oil fill hole. In both locations, neither of them could smell the scent of gas. Overall, the level was just a little higher then the upper mark on the dipstick. So, this all leaves me with a few critical questions:

1. If the oil does actually contain some gas, exactly what route did the gas take to make it down into the crankcase?
2. Since buying the bike, I have put about 300 miles on the bike. If there is gas in the oil, do any of you think that I now have crankshaft or bearing damage from the gas?

3. After the test with my wife and son, I purchased Shell Rotella T6 Synthetic oil and a new filter, as well as new NKG plugs. I'll want to make sure I get a solid drain of the old oil first, so do I also need to remove the oil cooler and drain it separately to ensure I get all the gas removed? What about gas contaminated oil that might be present in the clutch plate housing? Do I have to remove that as well to ensure it's fully drained?

4. Considering all the issues I've had with this bike since day !, do any of you think I should just cut my losses and sell the bike now? Keep in mind the fact that I obviously do not have the "experience" of wrenching on this bike like many of you seem to possess. One other possibility I've been considering is to pick up one of the complete carb assemblies I've seen posted online (Ebay, etc.). With my eyesight as it is, I would have a lot less trouble swapping out the entire assembly rather then pulling mine and going thru it. I have had offers from some members to go thru it for me, and I appreciate that very much. Just trying to minimize my expenses at this point, since I obviously overpaid for an ill bike. It is 20 years old now, and I'm wondering if the gas in the oil has eaten away at any of the internal gaskets, etc.

Thanks for any input everyone.

 

If there is gas in the oil, it likely got there due to one or more carbs flooding, due to a sticking float valve. Drain the crankcase and replace the filter, the oil in the oil cooler should drain with the rest of the oil. (A small amount may remain, but not enough to be a problem.) Then bite the bullet and remove the carbs and give them a thorough cleaning. I fought the idea of removing the carbs on our vfr700 for quite a while, doing the seafoam and techron thing for many tanks of fuel. It didn't help. I finally gave in and, following toecutters excellent guide, got the bike running very well. I ended up pulling and cleaning the carbs 3 different times before I got everything sorted out, and that first time I was very nervous. The 2nd and 3rd times were a breeze. I just wasn't thorough enough the first 2 times.

One note, if you aren't sure if the carbs have been off of the bike before, get some new rubber insulator boots before you start. If the ones on the bike are the original 20 year old pieces, they are going to be very brittle and will make removal and installation a real bitch.

 

1) Gas gets in the oil through the combustion chamber. It runs by the rings, which can not hold it back and so ends up contaminating the oil. An overflowing carb is the most likly culprit.
2) If it takes a third part to smell gas in the oil then there is not much and so you haven't damaged anything in the short time you have ridden it.
3) No
4) If you don't have the tools or the experience get rid of the bike. You will never be comfortable trusting it for long rides and you will not enjoy it.

If you decide to keep it you are going to have to get into the carbs to get it right. Just start and do it! It looks like a nightmare but it's really not bad.

 

Agreed. You shouldn't need to worry too much about the fuel causing Damage. It doesn't seem like there's alot in there.

Just do an oil change once everything is all sorted and the bike is running again.