? About fuel system diagnostic check

[juntjoo]

So following Haynes instructions i'm checking the fuel system and the first thing it says is to listen for a whirring noise at the gas cap when you turn the ignition to the 1st position but i'm hearing nothing. So what does that mean, because my car runs, it's just doing so with some stuttering issues, especially with the AC going.

There are a bunch of other steps after, but i'm just curious what this means before I move forward

 

[juntjoo]

Okay, I'll try that later. Here:

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[juntjoo]

Oops, it says analog. I've got digital.

 

[NHerron]

Hey I don't mean to step on toes here but there is a VFAQ on checking codes for obd1
ECU Code Checking

You can do it with an ANALOG multimeter (the one with the needle, not digital)
Or the buzzer mentioned in the link
Or a red LED with a 560ohm resistor

My 2G has your similar symptoms with the coolant sensor unplugged, I don't know about 1G however

 

[nickk90]

You can rent a fuel pressure test kit from autozone. It will come with a adapter for you to remove the bango bolt from the fuel filter and install a adapter in place of the bolt.

 

[steve]

So following Haynes instructions i'm checking the fuel system and the first thing it says is to listen for a whirring noise at the gas cap when you turn the ignition to the 1st position but i'm hearing nothing. So what does that mean, because my car runs, it's just doing so with some stuttering issues, especially with the AC going.

There are a bunch of other steps after, but i'm just curious what this means before I move forward

It means that the Haynes manual is wrong, no big surprise there.

The 1G doesn't run the fuel pump until your cranking the engine or the ECU sees pulses from the CAS. So people have noticed that their cars seem to prime the pump when you turn the ignition on but that's random likely due to the CAS glitching when power is applied and not by design.

 

[slonkey]

Lol I was about to say. Who has a analog. But I have a real old one too

Hey I don't mean to step on toes here but there is a VFAQ on checking codes for obd1
ECU Code Checking

You can do it with an ANALOG multimeter (the one with the needle, not digital)
Or the buzzer mentioned in the link
Or a red LED with a 560ohm resistor

My 2G has your similar symptoms with the coolant sensor unplugged, I don't know about 1G however

Thanks for the input but I think it's a few things that arnt working, a vac leak and some sensors. Together. Like 3 sensors and a big vac leak. Maybe pump going out.

It means that the Haynes manual is wrong, no big surprise there.

The 1G doesn't run the fuel pump until your cranking the engine or the ECU sees pulses from the CAS. So people have noticed that their cars seem to prime the pump when you turn the ignition on but that's random likely due to the CAS glitching when power is applied and not by design.

Didnt really think about it till now but he's right. 1g don't start to pump till the car is getting started.

 

[juntjoo]

So I stuck my digital multimeter to the terminal to read the codes figuring it must work the same as an analog one just maybe more difficult to read, which it proved to be so, but for what it's worth, after a lot of time watching the results I came up with four different codes; 12, 13, 24, & 25, volume air flow sensor, intake air temp sensor, vehicle speed sensor, and barometric pressure sensor respectively. So I'll start testing this stuff...

 

[1983gsp]

Sounds lime a bad maf or poor connection to the maf.

 

[juntjoo]

Turns out my digital multimeter has this audible setting that just buzzes the codes out. Awesome! Works better than an analog dial I bet.

Edit: no code 24, just 12, 13, & 25

 

[juntjoo]

Okay, what I don't get though is this: Haynes says to check voltage at the wire harness, with it disconnected from the MAF with ignition on "on" (and other probe grounded) which there is none(at terminal two, top middle one) and that if there voltage is incorrect the MAF could be faulty, but how am I checking the MAF if it's sitting next to me and i'm not even touching it? And wouldn't that indicate a problem elsewhere in the circuit between the battery and the MAF connector?

F Haynes. I'm taking my research elsewhere.

 

[slonkey]

Sounds lime a bad maf or poor connection to the maf.

That's what I thought but he said he unhooked it and didn't change anything

Okay, what I don't get though is this: Haynes says to check voltage at the wire harness, with it disconnected from the MAF with ignition on "on" (and other probe grounded) which there is none(at terminal two, top middle one) and that if there voltage is incorrect the MAF could be faulty, but how am I checking the MAF if it's sitting next to me and i'm not even touching it? And wouldn't that indicate a problem elsewhere in the circuit between the battery and the MAF connector?

F Haynes. I'm taking my research elsewhere.

Lol I say a short in the maf wires. I really think it has a air shortage. Saying it smells like gas and all. That means you are getting good gas pressure. Just spark and air. U said u replaced spark plugs and wires right? Well air is last...

 

[steve]

Make sure the MAF is plugged and and reset the ECU by pulling the room fuse or disconnecting the battery for second or two.

If the codes come back then you have a problem. Right now they could be from earlier testing if the ECU was on while the MAF was disconnected.

 

[juntjoo]

Make sure the MAF is plugged and and reset the ECU by pulling the room fuse or disconnecting the battery for second or two.

If the codes come back then you have a problem. Right now they could be from earlier testing if the ECU was on while the MAF was disconnected.

Good point. I may HAVE left the MAF unplugged. Will retest

 

[slonkey]

Make sure the MAF is plugged and and reset the ECU by pulling the room fuse or disconnecting the battery for second or two.

If the codes come back then you have a problem. Right now they could be from earlier testing if the ECU was on while the MAF was disconnected.

By a second I believe he ment 20 mins or so. I think it takes 20-25 mins to reset it, right?

 

[juntjoo]

This thread originally was about fuel pressure testing so I opened another thread about my codes issue ( http://www.dsmtuners.com/forums/mai...ion-about-codes-12-13-25-a.html#post152977220 ) and at this point I'm checking other things unrelated to those codes for the time being

 

[steve]

By a second I believe he ment 20 mins or so. I think it takes 20-25 mins to reset it, right?

No, the charge in the capacitors drains off pretty quickly. Why don't you try it and see.

 

[slonkey]

No, the charge in the capacitors drains off pretty quickly. Why don't you try it and see.

Well I do all the time. Adding and stuff but I thought a full restart took longer

 

[steve]

Well I do all the time. Adding and stuff but I thought a full restart took longer

Then you should have noticed that your fuel trims were reset along with all other long term setting. Ask any 2G DSMLink V2 user.