Thermal IAC

[fixkick]

Hi, thanks for the prompt reply!
I was able to seal up my throttle body/thermal IAC
Still experiencing the issue where the idle drops and comes back from cold to hot engine.
So I guess its a bog on cold start?

Fuel pressure seems ok according to your tests. 40psi with key on, engine off, 34-36 psi with engine running hot.
Only thing that seems odd, is when the gas pedal is tapped, fuel pressure jumps to 60 and drops back down.
Does that seem normal?

Thanks again for any and all help!

that 60 is wrong , 60 is shunt pressure, with FPR, stuck closed.  bad FPR, if 60 is real.
the key on pressure was 40 and that is normal and then at idle is 35 is ok.
but when you WOT the throttle, the pressure will go here  40 but not exactly, it will try to reach 40  on this car.
The 60 is only the shunt valve ,like when you block the return hose on the FPR.
Sounds like the FPR is bad. to me. (its sticking inside, does the vacuum port to it leak fuel if yes the FPR is bad.


here is mine at sea level 16valve engine. only. yours  is 4psi higher, and that is ok.  so 40 on your car would be max. for key on and WOT, (near)  green in imperial measurement USA.



60psi is when the pump works in to a dead head,  into a fuel line 100% pinched off or clogged.  show the pump working nice sure. but FPR NOT.  (spec max pressure is 43psi per FSM and is key on only spec)

Well, I fixed my idle drop. I still get a bog on cold start, and hesitation when going into first gear from a stop. I replaced the FPR, as well as the fuel filter. The 60psi jump is still there.
Would replacing the fuel pump strainer make a difference?
I would like to avoid replacing the fuel pump if it is unnecessary.
The car is OBD1, is there any way I can read the ECU logging?

Thanks again,
 I Appreciate any help!
you replaced parts, and did not repeat checking all test data.
key on pressure, idle pressure and WOT pressure? PSI (done at what test port. (rail or filter port?) IDK how you do your tests, please tell that. first.



Wow, that 60psi thing is very very odd.,  where is the gauge mounted? (rail or filter port)

60PSI is shunt pressure, this is only caused by a few things, 60psi.
at the fuel filter test port ? are you? there?, the pressure port tap is at the input of the filter, not the exit.

that means if the filter clogs that port goes to 60 (bad filter) or any crazy PSI not spec, never low but always too  high due to that clog (classics this is no filter service done)

if testing at the fuel rail,  test port KIT used,?, then that point is after the filter (this system is a loop,) this is true PSI at the injectors actual. 
if the filter is fresh and new both ports read the same,  as one would expect.

The FPR stuck closed you get 60psi.
if the FRP return line is clogged, bend or crushed all the way to the fuel tank , 60psi will happen. but stays there,
Any time you bump the throttle pressure does rise. but you did not tell all pressure, nor test port used.
The gauge you have can be bad. does it return to zero, not connected?  I have shop air and set my air regulator to 30 psi and connect it to my fuel pressure gauge to prove  the gauge is not fibbing. (SOP)

Cause list 60PSI

1. FPR bad (or some new china clone crap sold on fleabay at dirt cheap prices) or sold as new but is used.(so called refurb junk) or FPR molested (ask)
   
2. FPR Return lines, clogged/crushed. (even at center of car on pipe at frame rail or at tank port return)
   
3. Filter clogged, if test were done at filter where they.
   
4. wrong pump,  seen one guy use  pump off  FORD Crown Victoria and was so powerful (flows crazy high) and this pump overpowers the poor FPR and the FPR is helpless.  dang !
   

A  pump sock bad (clogged) makes low fuel pressures, never high.

"happens when the gas pedal is tapped",(pumped?),  when you do that vacuum drops, very very low.(low vacuum HG is normal with TV open)
vacuum at zero HG is 36psi (yours would read keyon pressure 40PSI (your old FPR did this,, new not told yet) by your own tests data)

I have no idea at all how your FPR works this way,  The FPR is very important element on all 16valve 4 injector engines.
this device, keeps pressure correct at all times, and is never ever at 60PSI ever.  

at idle the mine was newer 30PSI. in the middle of the 15PSI range (36-21= 15) psi.   but does very by altitude at sea level up to 18,000 feet.
at 18000 feet fuel pressure goes LOWER not higher !
but there is no cause  of 60PSI, other than what I stated above.

I have no idea at all what parts are on this car, these cars are old and many have flat wrong parts. (no suzuki parts stores here in USA< down to just 2 I think so parts are hard to get.)

60PSI is dead wrong if the guage is good.  for sure. we need to find this and fix 60PSI first,   But what are your other PSI readings off new FPR
where did this FPR new come from,  ofF  A wrecked car, I can not know where parts are found. (and parts MATTER)

Historically:
There are many of these cars with a bad FPR now, they are all due to fail and most did by now.
(sticks, leaks or its diaphragm is cracked)


at 60psi the injectors will inject 2 times normal flow and flood the engine. totally OVER THE TOP WRONG, fully.   But very interesting problem first ever I think , no 2nd.
that would cause gross flooding and misfiring not bogging, (lean is bog) misfiring is violent, not smooth loss of power like any lean engine does.
one guy here stuck bamboo slivers in the FPR to gain pressures (was too low) and lets just say , he was too successful and hit 60,,, sad story.... that... in Nepal.

if you want to see lean fuel results, just pull the FI fuse running (no not driving) and witness first hand LEAN BOG ANd stalls.