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Discussion Starter #1
My lifted 99 Prerunner gets bad gas mileage . It always has . I chalk it up to bigger tires . 6 inch lift and a rear end thats a special bo7a slightly lower gear from factory. Mechanic told me that the pump works extra hard thats why they die . Some of the problem is that 1 or 2 where defective. Anyway symptoms are no hot start . some stutter and sluggishness . Each time this happened it was the pump. Question is what would a slight upgrade on a pump be . A larger pump could handle my 12 mph . Stupid question is does the system act like my Ford where the gas circulates and excess goes back into the tank . I just changed my very dirty 100,000 mile filter. All suggestions welcome thanks Lloyd
 

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Mambeau / Admin
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I'm having a hard time understanding what it is about your truck (bigger weight; lift) that's making the fuel pump work harder. :shrug:

Did the mechanic explain how that happens?
 

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Discussion Starter #3
It has always got bad gas , he never said why no check light. 256.000 miles by myself. All I can think of is KnN cold air. A regular pump way not be able to handle 12 bucks of gas a day. What do you think???
 

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Mambeau / Admin
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Besides the K&N cold air intake, do you have any other engine or performance mods?

If so - what are they?

What are the details on the larger tires and the modified rear end gearing? Unless you've done some re-calibration to adjust for the different tire diameter and / or gearing the ECM is trying to adjust the fuel / air mixture for the wrong speed. This alone may explain the miserable gas mileage.

I can't help but wonder whether fuel pressure problems have something to do with it. Have you definitely ruled out a fuel leak somewhere? I'm still hung up on wondering WTF would wear out fuel pumps, and an over-pressurized fuel flow might explain it by increasing the load on the pump.

If one or both these angles is what's happening, I'm even more baffled as to why the ECM isn't throwing one or more codes.

I suppose there's a combination of problems that would leave the ECM "blind" to the actual situation while over-driving the pump and fool the ECM into never throwing codes, but that seems like too much of a wild coincidence.
 

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Discussion Starter #5
Do you think a Walbro 225 will fit ? Just for the record I have my exhaust cut off at the axle . Still have a cat . Magnaflow muffler. I think the cold air has something to do with it . I dont go to far , an you never know when your truck will be taken out driving in Fla. So Im used to it . Let me ask ls the hot start issue part of a bad pump. You never know if you were lied to.
 

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Mambeau / Admin
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If there's something wrong with the fuel feed from the tank to the engine it might help explain the hot start problem.

You mentioned "bad gas"...

Have the fuel lines been checked for kinks, crud or obstructions? That might explain most everything you listed.

Has the fuel pump wiring / circuit been checked? If occurred to me that if the lift (or age or whatever ... ) had screwed with the wiring the pump problems might be connected with voltage or resistance weirdness.
 

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Mambeau / Admin
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I'm not sure the cold air intake is the root problem, but it may be throwing something off and helping to camouflage where the root problem lies.

Do you still have your stock air intake stuff? If so, it might be informative to swap the OEM intake onto the engine to see what (if any) difference it makes.

One thing that occurred to me is that the ECM is struggling to provide a lot of fuel to match a lot of air it's detecting.

... Which also means your air / fuel sensor stuff may be involved.
 

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Discussion Starter #8
I thank you for your help . I just ordered a Walbro 225 fuel pump . Installation will be done by myself . I will be blowing all the lines out with compressed air. Will be doing other things you suggested . It has always been regular pumps. Probably Advanced Auto house brand . I will report back on how it went. One of the reviewers suggested more power , and smoother acceleration. Im considering mass air replacement . Would I need that with no engine light on . Dont know how to test . Over my head Thanks for the help.
 

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Mambeau / Admin
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I don't know about the MAF replacement ... I guess it can't hurt, but ...

So far you haven't demonstrated the air intake / flow is part of the problem. I mentioned it because it's the only engine mod you've got and something screwy with your air / fuel management might explain the miserable gas mileage and overworking the fuel pump.

If the air intake were part of the problem one would think there'd be codes getting thrown. If the ECM is blind to air / fuel problems, that suggests there's a sensor or ECM problem somewhere.

The only thing we know for sure is that you seem to be going through a lot of fuel pumps.
 

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Discussion Starter #10
Fuel pump is on Walbro 225. I could not get one of the bands on. Going to try again. Helps when your lifted. Here is the bad news now my gas guage does not work . Enola hoe sensitive is the vain that goes in the tank . Maybe when I drive to work tomorrow it will loosen up.
 

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Mambeau / Admin
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... Here is the bad news now my gas guage does not work . Enola hoe sensitive is the vain that goes in the tank . Maybe when I drive to work tomorrow it will loosen up.
I'm not sure. The fuel sender gauge (the all-in-one float arm and sensor unit) is one of those components the FSM never describes in any detail.

How is the fuel gauge not working? Does it register anything at all? Does it stay in the same position all the time (from ignition start through driving on the road)?

If it's totally "dead" (no reading from ignition start to igniton off, with or without driving) I'd suspect an electrical issue. Are you sure you got everything re-connected tightly when reassembling and installing the pump / sender assembly?
 

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Discussion Starter #12
I found it very difficult to get the gas tank back in. I dont know if only the Prerunner has the gas tank cover , but aligning the tank inside the cover was tricky. If my truck wasnt lifted 6 inches it could even be harder. To do it in the driveway on your back you would need two or three jacks. My pressure line was crimped and I didnt know it so it was cutting out a little. Had to bend it a little. Problem of starting fixed but something is off. Shifting is a little off. I think the computer is still learning a little.
 

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Mambeau / Admin
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I found it very difficult to get the gas tank back in. I dont know if only the Prerunner has the gas tank cover , but aligning the tank inside the cover was tricky. If my truck wasnt lifted 6 inches it could even be harder. To do it in the driveway on your back you would need two or three jacks. ...
I'm not sure what "cover" it is that you're referring to ...

Do you mean the skid plate underneath the fuel tank? If so - it's a standard part on all 6-lug Tacos from 1995.5 - 2000. 5-lug 2WD Tacos of that period don't have it.
 

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I found it very difficult to get the gas tank back in. I dont know if only the Prerunner has the gas tank cover , but aligning the tank inside the cover was tricky. If my truck wasnt lifted 6 inches it could even be harder. To do it in the driveway on your back you would need two or three jacks.

Which is why many people resort to lifting one side of the bed to access the top of the tank instead of removing the fuel tank from underneath
 

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Discussion Starter #15
How heavy is the bed ? A one person slide? I need to go back in because something happened to my meter and Im not going thru that again.
 

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How heavy is the bed ? A one person slide? I need to go back in because something happened to my meter and I'm not going thru that again.
When I put the Walbro in tank fuel pump in my 2001 Tacoma it took two of us to lift and slide the bed back to get to the top cover of the fuel tank.

Mad Maxx
 

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Discussion Starter #17 (Edited)
I have a small bed . Im going to try it tomorrow.I cant live with no fuel gauge . When I pulled it out the whole assembly got caught and I pulled a little hard . One of my biggest lesson learned ,that I have to always work on while working on my car hobbies are patience , and organization . Im going to put a new convertible top on my Foxbody Mustang. Its on the way , and its like a puzzle. Got a step by step dvd on the subject.
I want to put several pics on here but they come out sidways how do I turn them. They work on other websites
 

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Discussion Starter #18
Its better than nothing. Pictures are what make the sight cool!! I have had this 99 Tacoma single cab truck for 23 years . I put more than 200,000 miles on it and of coarse very little problems . Four fuel pumps Four batteries. Five sets of 32/ 11 1/2 15 Bfg all terrains . I put a Street Scene roll pan on myself. Did all the work myself. six inches of lift . Hope I have it for at least five more years. The price of a used Tacoma is crazy . I bought this for $10,000 dollars twenty three years ago . I could get six grand anytime here in Florida . Still going for more pictures on a new post.
 

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I have a small bed . Im going to try it tomorrow.I cant live with no fuel gauge . When I pulled it out the whole assembly got caught and I pulled a little hard . One of my biggest lesson learned ,that I have to always work on while working on my car hobbies are patience , and organization . Im going to put a new convertible top on my Foxbody Mustang. Its on the way , and its like a puzzle. Got a step by step dvd on the subject.
I want to put several pics on here but they come out sidways how do I turn them. They work on other websites
Here are your pictures Pete and see if they are turned around now.

Mad Maxx[/ATTACH]
 
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