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Drew
Drew, Super Mazda Tech.
Category: Mazda
Satisfied Customers: 2188
Experience:  19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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Have 1987 b2200 mazda truck A/T crew cab fuel pump not

Customer Question

Have 1987 b2200 mazda truck A/T crew cab fuel pump not running have droped tank from truck pump will run with power apply ed to black/red/strip could it be the ECM UNIT .
Submitted: 6 months ago.
Category: Mazda
Expert:  david craig replied 6 months ago.

Hi Im David, thanks for visiting the site. where are you applying power from at what connector or relay?

Customer: replied 6 months ago.
At the yellow plug fuel control unit on black/red wire
Expert:  david craig replied 6 months ago.

ok, allow me to pull up a print of your vehicle, thanks.

Customer: replied 6 months ago.
Have also looked for bad spots in ecm cannot find print in shop manual .
Customer: replied 6 months ago.
If you call me I am not in shop and will this cost more $
Expert:  david craig replied 6 months ago.

if a call is placed it will cost more. give me a few to look at a print, thanks

Expert:  david craig replied 6 months ago.

check the 10 amp fuse

Customer: replied 6 months ago.
Fuse good 11.6 using power probe
Customer: replied 6 months ago.
In shop at truck now
Expert:  david craig replied 6 months ago.

whats the battery voltage?

Customer: replied 6 months ago.
Print sent look the same as shop chiltons
Customer: replied 6 months ago.
12 at battery 11.6 at fuse
Expert:  david craig replied 6 months ago.

actually from mazda service manual

Expert:  david craig replied 6 months ago.

that voltage needs to be higher at battery so we can see if the voltagew at the fuse changes. i dont like the 11.6

Expert:  david craig replied 6 months ago.

did you check the grounds?

Customer: replied 6 months ago.
What am I missing this unit right of steering under dash have had tank away from mounting and on stand with ground and power wire hooked up can apply power on fuel pump control module and pump will run
Expert:  david craig replied 6 months ago.

have had what away?

Customer: replied 6 months ago.
I would think ground is good have installed new key switch control module for fuel also replaced
Customer: replied 6 months ago.
Tank not in truck at this time
Customer: replied 6 months ago.
Charger on truck now have 13 at fuse
Expert:  david craig replied 6 months ago.

ok good

Expert:  david craig replied 6 months ago.

i think if you follow that yellow wire back from the fuel control module or do a continuity check of that wire, you'll find the problem

Customer: replied 6 months ago.
Does the yellow wire used for the gauge of fuel in tank
Customer: replied 6 months ago.
David does this truck have a rollover switch and if so where
Expert:  david craig replied 6 months ago.

let me look that info up but im fairly certain it doesnt

Expert:  david craig replied 6 months ago.

well it has a fuel pump cut out relay....

Customer: replied 6 months ago.
Is there also maybe a bad fuse able in the fuel wireing
Customer: replied 6 months ago.
what u thing next check
Expert:  david craig replied 6 months ago.

theres no fusible links in the circuit.

Customer: replied 6 months ago.
Where is that relay loc.
Expert:  david craig replied 6 months ago.

you need to start doing continuity checks from the fuse to the fuel pump control unit. from the feedback control unit to the fuel control unit and from the fuel pump cut out relay to the control unit. test for continuity and shorts to ground

Customer: replied 6 months ago.
Well that is alot to check. Have been on this all day is a starting point will start tomorrow thinks and can we talk later email me any thing that might me helpful just come fix this truck thanks in advance Roger
Customer: replied 6 months ago.
Where are the test points and components loc.and wire harness run from and to
Expert:  david craig replied 6 months ago.

The electric pumps dont ground with a wire per se, there is a wire coming out of the tank from the pump but it terminates on the mount. If you moved the tank, you have to be sure the tank itself is grounded, it works like a big wire, the ground path from the frame travels through the metal of the tank and to the point the fuel pump is grounded.

Expert:  david craig replied 6 months ago.

make sure that tank has a good ground.

Customer: replied 6 months ago.
The ground black thru tank from inside tank pump assy. Goes thru plug that ground is good.
Expert:  david craig replied 6 months ago.

ok...the fuel pump relay is at your left foot behind the the plastic cover, but I really think the problem is the fuel pump driver inside computer does not stay engaged long enough for the relay to close the contact.

Expert:  david craig replied 6 months ago.

im looking back at some old mazda records i have. inside the computer theres a capacitor that is very subject to overheating and melting.

Customer: replied 6 months ago.
David I have had ECM out look saw nothing no hot spots with the jumper in D and B on fuel pump control unit pump will run all the time.would it b safe to say ECM You think bad an where would you get one ready to plug and play
Expert:  david craig replied 6 months ago.

https://www.autopart.com/ecc/ECC1987MAZDAB2200.htm

Customer: replied 6 months ago.
David 1:30 am have tank in truck cycle key about 25 times will run until fuel runs out reveling motor 2 br. Might come in spray of gas low shut off do same step will do the same any thing to mind is this a sign of bad ecm I can hear pump when key cycled listened in tank hear nothing?
Customer: replied 6 months ago.
Have a good night will try to look for some info. Thanks you have helped more help needed
Expert:  david craig replied 6 months ago.

are you getting power TO the fuel control module?

Customer: replied 6 months ago.
What wire should have power can hear pump each cycle of key will run out of fuel what happens after truck turning over telling fuel pump on all the time run till engine switch turned off?
Customer: replied 6 months ago.
Not at truck now having coffè
Customer: replied 6 months ago.
Leave me your thoughts we reach out in a few
Expert:  david craig replied 6 months ago.

black and white wire at fuel pump control unit. check voltage reading. then check the grounds for the module.

Expert:  david craig replied 6 months ago.

just checking in to see how its going.