Sudden MPG drop, HELP PLEASE!!!

okkool77

okkool77

New member
Ok guys, since I've had time off from work its left me with more time to wrench on the Scout and thus I've run into new problems.
Anyways, I've noticed a sudden drop in my mileage as of the other day. I went from around 14 mpg to 7.5 mpg around town.
I'm running the aftermarket 19 gal. Poly tank with an electric fuel pump on the frame rail with all new hose running to the carb and new fuel filters so this should be able to rule out crud from getting into the carb and messing with the jets and such.
The motor has a still new (3 months old) weber 32/36 and it has been giving me a very consistent 14 mpg and I have a very heavy foot.
Other info: 232 I-6, hei distributor, new plugs and wires.
Now I'm wondering what would/could cause such a sudden drop in mileage so please throw those ideas out there and I'll check them out tonight and tomorrow.
Thanks guys.
 
okkool77 said:
ok guys, since I've had time off from work its left me with more time to wrench on the Scout and thus I've run into new problems.
Anyways, I've noticed a sudden drop in my mileage as of the other day. I went from around 14 mpg to 7.5 mpg around town.
I'm running the aftermarket 19 gal. Poly tank with an electric fuel pump on the frame rail with all new hose running to the carb and new fuel filters so this should be able to rule out crud from getting into the carb and messing with the jets and such.
The motor has a still new (3 months old) weber 32/36 and it has been giving me a very consistent 14 mpg and I have a very heavy foot.
Other info: 232 I-6, hei distributor, new plugs and wires.
Now I'm wondering what would/could cause such a sudden drop in mileage so please throw those ideas out there and I'll check them out tonight and tomorrow.
Thanks guys.
Click to expand...

If that is truly the correct mileage numbers, then that carb has to be running majorly Rich overall. And not just in the cruise mode but in all modes. Are you certain the choke is opening all the way??

There are many versions of the weber 32/36 and it's clones, which exact version do you have by model number/choke system/and primary throttle actuation position???

The float needle in the spanish webers are shit. And most all webers sold in the u.s. In the last 10 years are spanish production (along with chinese). The best needle/seat to use are the parts actually manufactured currently in italy. The most common weber 32/36 rebuild kits (along with the cheepest) are the "empi" brand which the vw folks scruu with, those are total shit and come out of china, they internals are extremely poor quality and can't resist e10 at all.

The spring-loaded "ball" on the needle sticks and fails, thus the fuel level increases drastically to the point of raw fuel running down the throttle bores.

Also, if the float is the hard foam nitrophyl unit, it has possibly absorbed fuel, those floats can't deal with the shit e10 the government has forced into the market place. I don't have gram weight on the oem nitrophyl float, but I'd say 13>14 grams is ballpark for a good one. A new brass float will weigh slightly less.

Can the e10 attack a carburetor in just a few months??? How about justa few weeks?? I personally feel that some of the internal materials in the current weber stuff has no resistance to e10 deterioration.

Currently the best source for weber parts I'm aware of (and I deal with these folks myself) is:

pierce manifolds
 
Yes those are the correct numbers from before, however I have never been able to get it to run with better numbers since the whole motor is on the way out and I drive with a very heavy foot.
I purchased the carb from john at jam engineering right before Christmas. Its the 32/36 dgev w/ an electric choke.
I'm open to suggestions that I can try before rebuilding the carb since I'm in between paydays and this is my dd.
 
Last edited:
okkool77 said:
yes those are the correct numbers from before, however I have never been able to get it to run with better numbers since the whole motor is on the way out and I drive with a very heavy foot.
I purchased the carb from john at jam engineering right before Christmas. Its the 32/36 dgev w/ an electric choke.
I'm open to suggestions that I can try before rebuilding the carb since I'm in between paydays and this is my dd.
Click to expand...

Suggestions? The carb is broke! It needs to be serviced and determine what is wrong. There is no magic bullet! It's dam simple to remove the bowl cover and look at the float needle and verify fuel level.

Are you certain the electric choke is operating correctly as the engine warms? Is it pulling off and holding fully open when the engine is up to temp?

The electric choke version is far superior to the manual and hot water choke systems. But...the entire choke operating system on these weber carbs is shit and failure-prone, mostly regarding all the linkage components. Then the plastic plug in the end of the air horn disappears and allows dirty air to bypass the air filter.
 
michael mayben said:
suggestions? The carb is broke! It needs to be serviced and determine what is wrong. There is no magic bullet! It's dam simple to remove the bowl cover and look at the float needle and verify fuel level.

Are you certain the electric choke is operating correctly as the engine warms? Is it pulling off and holding fully open when the engine is up to temp?
Click to expand...

I got the part that this damn thing is broke, I was just asking if there was anything else I should look at in the mean time...
As for the choke, whats the easiest way to adjust it?
I've got all day to tinker with the damn thing so I can check it almost immediately once I read it here.
Thanks.
 
okkool77 said:
I got the part that this damn thing is broke, I was just asking if there was anything else I should look at in the mean time...
As for the choke, whats the easiest way to adjust it?
I've got all day to tinker with the damn thing so I can check it almost immediately once I read it here.
Thanks.
Click to expand...

Don't "adjust" the choke...ya verify correct (or incorrect) operation first! If the choke operation is not correct, then you correct it. What really matters is that once the engine is completely up to operating temperature, the choke is fully open and held open.

An electric choke is not dependent upon engine temperature whatsoever. The heating element operates on a pre-engineered curve, from the point that current is applied (key switch turned on), the choke will begin to heat and be fully open hard against it's stops in less than 4 minutes. When the key switch is turned off, then the choke plate should fully close within about 15 minutes.

The electrical feed to the choke cap must be from a switch b+ point, do not ever wire an electric choke to the positive terminal on the ignition coil.

If that carburetor was new, it should have been shipped with a set of instructions with basic information and troubleshooting for installation.

Have you installed a fuel pressure regulator on that engine to reduce the oem fuel pressure for the weber install? If not, that carb requires no more than 3psi fuel inlet pressure. The oem fuel pump produces 5>6psi which is the norm for most all oem carburetors no matter what brand they are. Unless ya have correct inlet fuel pressure on the dgev, the idle quality is shit and really cannot be adjusted properly at all, and the fuel level in the bowl becomes uncontrollable as the the float/needle/seat can't handle more than 3psi.
 
Last edited:
Ok, I just checked the choke as you specified.
The first picture is before the motor was running and I just switched everything on, the choke is connected to my electric fuel pump that puts out 3 psi. So when the pump comes on the choke gets 12v as well.
Second picture is after 1 minute of running.
Third is after 4 minutes of running.
Fourth is after 6 minutes of running and I revved the motor some.
dscn0718.jpg

dscn0719.jpg

dscn0720.jpg

dscn0721.jpg
 
Are the choke plates hard against their stops when fully open? If so, then that is not your problem. If they can pushed open hard against the stops with your finger while the engine is running, that is a problem.

I've never seen an aftermarket electric fuel pump that produces a solid/regulated 3psi unless it has a built-in regulator that can be confirmed for output pressure. The fuel pressure must be confirmed at the fuel inlet fitting on the carb while the engine is running at both idle and at 2500rpm.

All the electric fuel pumps I use/install (several different "brands" such as walbro, carter, facet, kem, Holley, even the shitball mr. Gasket, etc.) have an output rated at 4>7psi with no exact output pressure. For the weber, all those pumps must use a true fuel pressure regulator added in line and set using a fuel pressure gauge. Post a pic of your actual fuel pressure displayed on an analog gauge with the engine running at idle.
 
The choke plates can be opened further with my finger while the motor is running, I would say in that last picture the plates still had another 1/2" to 3/4" of available movement to go.
The pump that I'm running is one of the mr. Gasket ones, they claim that its good for vehicles with carbs.
I just ran down and tested the fuel pressure at the carb inlet and it reads 7psi, 4 more than what I should have.
What fuel pressure regulator would you recommend to pick up?
Here's the picture of the gauge while everything was running.
dscn0724.jpg
 
The "claims" for this stuff is just that..."claims" and marketing bullshit! Sum dam marketing intern (unpaid and in third year of work onna marketing degree)) for the advertising agency that handles mr. Gasket writes that crap that then gets printed in china. Mr. Gasket doesn't actually manufacture those pumps, they are just a private label deal. The facet version of that pump which is a sealed unit in a polymer housing I feel is far superior and about the same retail price.

That same "mr. Gasket" regulator is also shit ( have several). The tick marks on the adjusting dial don't mean nuthin'. Ya must use a fuel pressure gauge to set the regulator, then note the position irregardless of what any tick Mark might say. Once they are "set" with the aid of a gauge, they will maintain correct pressure. The regulators from Holley and the specialty suppliers are far nicer quality but even then they must be set/verified with a gauge. The 3psi spec for the weber is a complete anomaly in the world of carburetion used on street-driven vehicles where 5>5.5psi is the norm.

So adjust the choke cap so that the choke plates fully open when warmed up, you are running around now with the choke plates "closed" about 25% which greatly enrichens the mixture from idle all the way through the transition to the main jet feeds at cruise.

Once the fuel pressure is regulated properly, then adjust the idle mixture which is hugely affected by inlet fuel pressure on these carbs.

You can easily see/experience what a difference in idle quality that inlet fuel pressure makes, these are the most tedious carburetors I've ever experienced in that regard and it created problems for me also as I've learned what I know now about these mixers. With the fuel pressure set to 3psi, adjust the idle mixture. Then increase the fuel pressure with the regulator a small amount at a time and you can hear the idle quality deteriorate, if you had an exhaust gas analyzer rigged, you would see a huge change in the a/f ratio for the worse.
 
You need to search the web. I ran that same carb for many years and did all the tweeks to it lots of info out there. You need to search.
 
I haven't had a bad idle, or even a Rich smell (though that don't mean much).
The only thing that brought this whole mess of problems to my attention was the sudden drop in my mpg which I can see from the increased fuel pressure, thus blowing by the needle and flooding the carb.
But my real question is this: why did it take 3 months for this to finally show up?
 
okkool77 said:
I haven't had a bad idle, or even a Rich smell (though that don't mean much).
The only thing that brought this whole mess of problems to my attention was the sudden drop in my mpg which I can see from the increased fuel pressure, thus blowing by the needle and flooding the carb.
But my real question is this: why did it take 3 months for this to finally show up?
Click to expand...

Shit happens...especially with e10!
 
E-10, I'm assuming that this is the percentage of ethanol that is now put into fuel...
I was under the assumption that if you had less than 10% it wouldn't make that big of a difference.
Also, would this have effected the carb that I used to have on?
It was a 1940 Holley single barrel and I got a consistent 14 mpg with that one.

Edit:
I just did a google search on e-10 and I don't run that in this rig.
Here in Nevada, we don't have to worry about that...they still let us run real fuel down here.
 
Last edited:
E10 is the bane of the special interest automotive world for the last two years. It has also bankrupted the marine industry in the united states.

The alcohol component kills internal fuel systems components, along with any older fuel injection part it comes into contact with.

We've discussed this many times around here if ya do a search.

The Holley 1940 is also affected to a great extent, carbs have a useful life in daily service now of two years. I do a Holley 1940 build about once a week using nos kits produced more than 20 years ago.

One of my carb parts suppliers is trying to change over as much of their popular offerings to alcohol-resistant materials as possible, but they aren't going to toss out millions of dollars of inventory stretching back 50 years for special interest stuff for which there is hardly any market.

Use stabil marine formula (the blue liquid package) in order to kill e10. It works if you follow the directions implicitly. Stabil "red" formula has no effect on e10, and they make no claims that is does! Stabil is not snakeoil and is the only additive I've used in fuel supplies in my equipment for the last 30 years.
 
Ok, so let me get this right.
Start running the "blue stabil" from now on when I fill up.
Buy and run a fuel pressure regulator to reduce my pressure down to 3 psi.
And if all of that doesn't work, keep doing it and rebuild my carb.

Does that about sum it up?
 
okkool77 said:
ok, so let me get this right.
Start running the "blue stabil" from now on when I fill up.
Buy and run a fuel pressure regulator to reduce my pressure down to 3 psi.
And if all of that doesn't work, keep doing it and rebuild my carb.

Does that about sum it up?
Click to expand...

Using the marine formula stabil is our only defense currently against the debilitating effects of e10. Run it constantly???...I don't but I do treat all my portable fuel containers since that fuel normally doesn't turn over as fast as the fuel in my trucks. And e10 is destroying carburetor and fuel systems left and right on chainsaws, power equipment, outboards, etc.

But I'm not "normal", I'm in the "carburetor business"! My personal vehicle carburetion gets reconditioned every two years or as needed. And all our personal "modern", fuel injected computer vehicles are going away now, we'll never own anything built after jan. 1, 1980 again in our lifetime.

The weber dgxx carb definitely needs a 3psi input pressure, you should have been informed of that when ya bought the stuff. There are also quite a few tweeks that May need to be done regarding that carb when mounted on that rambler motor, I've never delt with that particular conversion but I'm currently deeply involved with ironing out many drivability issues regarding installing that same carb on ihc-produced 152 and 196 fourbangers, contrary to what the common wisdom amongst the vendors of these mixers blow smoke about, this carb series is not a "drop-on" replacement on those applications, those carbs must have some mods made and then be correctly jetted for each application depending upon other engine mods that May have been performed.

Once I'm confident that I know exactly what the "good" setup regarding these webers is, I'll post the mods, but right now I'm not confident all the stuff I've learned is valid until more work is done and then validated by running the systems onna exhaust gas analyzer (which I have).

But...the fuel pressure deal is valid and you can feel/hear the difference immediately when ya jack around with the regulator settings. Since you have the fuel pressure gauge, you are ahead of the game and can quantify what you see.
 
michael mayben said:
using the marine formula stabil is our only defense currently against the debilitating effects of e10. Run it constantly???...
Click to expand...

Hello michael. I got curious about e10, since I monitor the pure-gas situation at pure-gas.org (if you know of a gas station that sells pure gas in your area, add it to the list on there - you can do it anonymously). I'm getting closer to getting my Scout. And it appears that I live in a non-compliant area (read - big city) which requires e-10 at all pumps, apparently.

Is it true that I can get alcohol-resistant parts like carbs, tanks, and fuel lines?

What do I do as a yet-unschooled owner of my Scout II? I'm still learning a lot of things. What about using seafoam versus stabil? I'm reading that some people are using seafoam for driving and stabil for when the vehicle sits for days at a time. I want to use the right one for regular driving. I will be driving the Scout and the cr-v on a regular basis, driving each one half the time.

Thank you!
 
Last edited:
I run stabil marine formula treatment in my gasoline for all products that May sit for a time period. Been using stabil stuff for more than 20 years with no issues whatsoever. It's as effective for the chainsaw fuel as it is for anything else.

As for running any other product in the fuel, I never do that. I have no experience with any product added to my fuel supplies other than stabil.

Alcohol-resistant fuel system parts??? Only thing you can do is pay attention to what you have now and what May be replaced in the future. Soft fuel hose has a life expectancy of about 2 years. Most carburetor parts are becoming very difficult to obtain anyway, no one is making "alcohol-resistant" parts as there is no market for that unless the government decides there to be and they dam sure won't!

Some of the specialty/aftermarket folks are doing their old skool fuel pump kits/parts in some sort of alcohol-resistant materials, but those are pumps that are rebuildable, not at all what the pumps used on the ihc sv and I-4 engines are after about 1972 or so.

I really don't concern myself with this "alcohol-resistance" stuff at all. I just rebuild carbs as needed, that means much more often than we had to do a few years ago. So-called gasahol has been in the market place for more than 25 years in some solution or another. But a mandatory e10 blend is relatively new in many markets today.
 
You must log in or register to reply here.
Back
Top