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96 x90 revival
(11-21-2018, 08:57 PM)fixkick Wrote: Sorry the snap on fuel pressure guage reads 40 psi and then when you pull of the the vacume it reads 50psi


How is this wrong? When running the engine the fuel pressure is 40psi with engine vacume attached to regulator. When vacume is removed the fuel pressure regulator closes and creates more pressure?
No misfire , starts and runs great until it it reaches 800rpm, also see me reply on prior post ^^^
key facts on 1990's cars
ECU does not test the pump output ever,
nor the FPR output or regulation
only you can.

the 96 year can pop DTC for out of control fuel trim but you already know it is, and if you drove it 3 driving cycles that DTC may POP but is a moot point. YOU see the 02 is dead. stuck 1v.
keep in mind, i cant see car, no see wrong or missing /damaged parts on the car.
all i can do is test, .
from here.
Not sure what pump I put in. The fuel pressure is 40 psi while running, I'm at sea level Florida. When I pull the vacume of the fuel pressure regulator while running it raises to 50psi.
no, communications are clear after you told 02 is really 1v stuck and not 0.09v(0.1) stuck in post 1.
and the FPR tests are 4 test and more with balance testing.
you never did the 3 FPR range test not once, so all we have is one test at 50 that is wrong, 40 seems right but no full vacuum test done by you , on the FPR, so the FPR was never tested at , the least 3 data points, per post 6
Quote:I understand how the FPR works. I think we may have some communication errors between me and you.

The fuel pressure measured at 40 psi with the engine running.
With the engine still running and removing the vacume source away from the FPR it measured 50 psi. Can we agree that this is correct or not?
I told you the FPR range does not ever include 50 PSI.
your key on only pressure no start is wrong, and not once did you say that. it will be 50, same as above and is Dead wrong.
the FPR is a dynamic device,
from 0 vacuum to full (26"Hg ) vacuum.
if the pressure is not right (fuel) in that whole range the FPR is bad, why is that hard to understand
learn that the FPR keeps pressure (deferentially ) constant across the injectors, and does so for any throttle angle (vacuum) and for all changes in altitude (15k feet high fuel pressure are lowest )
ON MPI the FPR is a prime #1 suspect at all time for sure 22 year old relic, FPR's
I'm sorry I no longer have the snap on fuel,pressure rig in my possession. So running test are not available.

when testing it I removed it from the rail and bench tested the FPR and it held vacume no leak down?

I'm still not sure what your saying, you say my fuel pressure is to high at 40psi when 36 to 43 is spec?

Also one there is no vacume applied to the FPR while running its natural to see a higher reading?

Motor has good vacume reading 19-21 in/hg

One another note i checked for ground at the ECU on the sensor ground pin to verify ECU is getting a proper ground , checked out good. Also checked the ect reading at the sensor and at the ECU and checked out good.

I'm leaning back to having an injector problem even know there is no miss. Going to remove them and clean them and bench test them.
36-43 PSI, keyon, not started ( you may have to key on 3 times to build enough pressure, pump runs on 3 seconds) you told me 50, so is WRONG.
Running: 30-37 PSI , idling.
shunt tests, is 55psi, (return line pinched )
the full FPR vacuum test, is 21PSI (typical) (hand pumped to 26" inches vacuum (this checks the other end of FPR range, showing linearity is ok.
the leak down test is. that suzuki calls Residual :25 PSI , after 1min. drop test.(running then key off,how long does it hold) (finds injector or FPR leaks this)
the next test is fuel pressure, injector balance test, per the book, I have the book page links, for you.

at post 4 and 10 you had 50PSI , key on-no start , or with engine running pulled vacuum nipple on FPR and got 50psi, both those tests are wrong, (and really is same test,)
50 is wrong, I told you that it was wrong but you do not believe me,there is no communications errors,

key on pressure at 50 is 7 PSI too high, (that is a HUGE error 7)
did you remove the tank side GAS cap to see if that makes fuel pressure go good?

most these cars now have bad FPR, due to age, alone, endless posts here for it failing, some in horrible odd ways (sticking inside caused due to moving 1million times for 22 daily driven , these parts wear out, do you understand that?

the injectors can be clear by unltra sound, to get the impossible to clean screens clean at home, they reverse flow the injectors to do that

see Duane do the balance test. ?

see suzuki tell you how to do the balance test.? Gm book. volume 2, chapter, 6 E3 page c2
96-FSM-v2-6e3-c2-pdf. 26 pages, there, all very good.
page 9 pdf show the FPR 41psi rule and why,(the spring) yours read 50 so is WRONG. page 11 pdf shows 2 more FPR test.
the exact PDF pages are (balance test) are page 22 Plus, and the special tool (we use generic tool(


These injectors unpugged all read 10 ohms (about)
that means with 12vdc battery (it is) that 1.2 amps per coil or 1.5amps running,
do not hot wire the injector or they will burn up. power = amps times volts so 21 watts is dissipated, by the coil inside. 10 to 22 watts, not running or running. ok so do not burn up the injector hot wiring it, ok?
what a shop uses, as did the GM/suzuki book did clearly is use a device called an injector pulsers.
this acts just like your ECU and pulses injectors so that do not overheat, for above reasons, stated.
did you know all that?
its not too hard really with a helper at the KEY
so with the fuel fully charged key oh 3times,an at 41 pSI. (not 50, if 50 that is bad FPR)
we rail is charged as duane shows in its great video.
he then Pulses (tool) the 1st injector for until the pressures goes to zero and with a stop watch measure that time.
if all 4 injects take the same time to leak down to zero then the are in BALANCE.
if pressure was 50 the FPR is bad.
if it leaks down before the injector pulser is used then you have leaking injector , unplug all 4 now, still leaks now? that is FPR leaking or the fuel pump check ball inside bad, (rusted) to test the injector for balance the Residual :25 PSI , after 1min test must pass first. ok?

this is all MPI testing all shops know how to test MPI and doing FPR tests fully is #1, or the injectors will not inject the correct rates of fuel .

best is save this file, so you have it.

when testing EFI we do the tests and if one thing reads wrong, we do more testing to find out what is cause.
new $400 ECU fails;'
all other tests pass. (ECT, MAF, 180f water temps, scan tools tests, all pass, 02 stuck lean)
all but FPR tests, and not complete, all tests not done. (the full vacuum test NOT DONE)
what if 4x prof. cleaned injectors $88 does not cure the problem, ?
the FPR was $60 at rockauto, and is the cheapest fix on fuel pressure, and most or many are bad know, we know that, seen here vast times. NOW.
the FPR is complex in that it can fail many ways, for sure 22 years old why skip the KEY PART>? (the ECU can not test (DTC) it like on modern cars)

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