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Discussion Starter #1
I had my fuel pump replaced upon the mechanic finding poor fuel pump output, which didn't seem to fix the problem of my 2001 MR2 having difficulty starting & idling. Later it was discovered that the voltage to the fuel pump is reading around 4.7V, while it should be getting around the standard 12V, no?

What piece of equipment regulates the voltage to the fuel pump which could be failing, causing a low voltage reading at the pump?

We also knew my "cats" were likely clogged as well, due to the engine codes which had been coming up for about 2 years now. I've elected to try and get by for as long as possible without actually replacing them because I plan on doing a 2ZZ swap when this engine finally dies (it's at ~150k now).

So my mechanic removed the cat system & ran the car at idle for 30 minutes without issue. He is now planning to replace the upper manifold with a "cat-less header" for about $100 to help get me back on the road again. I'll manage in dealing with getting a waiver from the DMV after failing emissions inspections twice.

My concern is that even if this solves the starting/idling problem, doesn't the low voltage at the pump indicate the necessity of fixing that problem as well?

I greatly appreciate any help in this matter!

:cool:

bernard baruch carman
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The fuel pump should have 12V. How was the voltage tested?

The ECM supplies voltage to a relay that supplies power to the pump. You can test the relay, and if that is OK, it could be a wiring issue

73821
 

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Thank you both very much! I will share this page and/or info with my mechanic (i presume one can view this forum without being a member. ;-)
 

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Thank you all, the schematics were very helpful! The low voltage getting to the fuel pump seemed to have been remedied by replacing the relay.

Thus far, everything related to the fuel pump has been replaced EXCEPT for the "idle air valve", which sounds costly. I read somewhere to NOT use a clone for this part and to purchase a genuine Toyota part for this, or to expect troubles:


Yet, this might not even fix the problem of the engine not wanting to start. My mechanic had said that once he got it started, it runs rough idling, but runs better at higher revs.

The other known problem with my MR2 are the pre-cats being clogged up. One workaround he tried was to remove the pre-cats (or poke holes through them, i cannot recall) in order to try and get it running, but this didn’t seem to help — he did explain that doing so could certainly cause the computer to not send the correct fuel/air ratio, but i just wanted to try it anyway. Regardless, i’m not certain doing either of these expensive repairs will actually solve the issue.

The reason why i’ve not replaced the pre-cats to see what happens is because my plan is to purchase a low milage (~50k) 2zz engine, 6-speed trans, & ECU from Japanese Domestic Imports and do the swap.

Therefore, i am having difficulty feeling good about spending another $1000 or so on both the pre-cats & the idle air valve when the exhaust system (including pre-cats) will have to be again replaced — i have no idea whether or not the idle air valve is the same on the 2zz as the 1zz… is it? i understand the entire exhaust system will have to be updated on the rear mount 2zz, but have no idea which brand or product to investigate.

If so, perhaps i should go ahead and replace at least it, in order to see if i can get another 50k out of my 1zz (which is also making some kind of internal noise).

The other problem is that right now my mechanic is not able to do the swap due to health issues and the lack of a proper lift he would rather use for the project. Does anyone here know of anyone who has experience doing such a swap in the south east region? (i’m in Western NC.)

My mechanic suggested i ask on this forum what all is specifically entailed in doing the swap — what are the actual parts needed so that i can assess the cost & time to do the job.

BTW, he already installed a low milage 6-speed transmission from Monkey Wrench complete with that special linkage thingy to accommodate the transmission being rear mounted rather than front. At that time i didn’t know about JDI, or i could have purchased an entire 2zz engine with trans & ECU for nearly the same price Monkey Wrench charged me — UGH!!! But at that time my engine with nearly 150K on it ran fine with no signs of trouble at all, or i would have sought to do the swap then if possible.

Any help toward striving to make a good decision here would be most helpful. Thank again!

:cool:

bernard b carman
 

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I've had issues with fake/counterfeit items being passed off as OEM on amazon.com. I can't tell you for sure but this listing you linked looks like a fake listing. I would avoid it. Buy directly from a Toyota dealer. Many of them have online shops with discount prices. I suggest this one, it is very reputable, I have been buying from them for years:

www.partznet.com

Your other option, to save money, is to buy a used OEM unit from salvage. You can find salvage sellers on ebay.com and on car-parts.com. Many offer a short-term guarantee.
 

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...The other known problem with my MR2 are the pre-cats being clogged up...

...One workaround he tried was to remove the pre-cats ...

...or poke holes through them...
They don't tend to clog up. They disintegrate. Then they get sucked back into the engine, destroying it, or they blow downstream to the main cat, and clog that one up.

Often done.

Definitely not.
 
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