Fuel pressure

[Midnyteryder196]

I've watched may's vid on checking fuel pressure and checked mine tonight. In the vid he said 03+ were supposed to be 50-57psi. Just checking is that the same for the lwb? They have a bigger tank so didn't know if there was different specs. For the lwb as opposed to swb?

 

[Mounce]

I'd say it should be the same. Only reason it'd be different is if it uses a different pump.

Were your results off so you're worried?

 

[Midnyteryder196]

Oh yeah.. 32psi.. Lol. The lwb shows it takes a different pump.. So I was just wanting to see where it should be.. Although 32psi is way to low anyway..

 

[Mounce]

Different pump itself or different sender assemblies? Pumps might be the same even if there are different senders.

 

[Aarkon]

I looked them up and compared to my truck I cant even get a hold of the delphi pump for his

 

[Mounce]

After looking on oreilly's website, swb and lwb both have a flow rate of 21gph and are pressure rated at 59.46psi yet they're about $50 different for the whole sender assembly. Both delphi brand.

-so, I'm guessing the senders are different.

 

[Mounce]

SWB part #: FG0387
LWB part #: FG0411


Looking at '04 model years.

 

[Midnyteryder196]

Yeah and I bet they was like 350 or more huh Garth?

 

[MAY03LT]

I haven't seen diff'rent specs for swb and lwb. Is the engine running at 32psi?

 

[Midnyteryder196]

Yeah it runs pretty decent.. It just been having a p0171 code for a while now.. And now more frequently it hasn't been wanting to start up when warm

I rented a fuel pressure tester from oreillys.. And it said 32psi idling. Now wether the gauge was off or it really is 32psi I'm not for sure.. First time I've messed with a fuel pressure tester..

 

[Mounce]

Yeah and I bet they was like 350 or more huh Garth?

LWB was $346 or something, SWB was $299.99.

Let's just say...I hope my fuel pump never goes out with that being the replacement price.

 

[Midnyteryder196]

Delco mu1835 which is 237ish on rock auto.. 207 on Amazon.. The original lasted this long. Prob should just stick with oem huh?

 

[Mounce]

Yeah probably a good idea if you can afford it.

 

[coolasice]

Yeah it runs pretty decent.. It just been having a p0171 code for a while now.. And now more frequently it hasn't been wanting to start up when warm

I rented a fuel pressure tester from oreillys.. And it said 32psi idling. Now wether the gauge was off or it really is 32psi I'm not for sure.. First time I've messed with a fuel pressure tester..

Fuel pressure is tested with key on, engine off.

Important: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

Turn OFF the ignition.
Turn OFF all accessories.
Install a fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
Turn ON the ignition, with the engine OFF.

Important:
• The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
• DO NOT start the engine.

Command the fuel pump relay ON with a scan tool.
Observe the fuel pressure gage with the fuel pump commanded ON.

Is the fuel pressure within the specified range?


345-395 kPa (50-57 psi)

 

[Midnyteryder196]

Fuel pressure is tested with key on, engine off.

Important: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

Turn OFF the ignition.
Turn OFF all accessories.
Install a fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal .
Turn ON the ignition, with the engine OFF.

Important:
• The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.
• DO NOT start the engine.

Command the fuel pump relay ON with a scan tool.
Observe the fuel pressure gage with the fuel pump commanded ON.

Is the fuel pressure within the specified range?


345-395 kPa (50-57 psi)

Okay I didn't do all of that.. Just followed may's video and did that.
I did happen to notice that fp wen key was turned on a few Times before it started was around 25psi

 

[MAY03LT]

I double checked the specs and there is nothing separate about the LWB. This is part of the fuel system diagnosis page where the pressure is between more then 0 and less then 57. I've never had one of these with fuel pressure between those values, it's been either good or none. My first thought is to try another gauge before doing anything.

 

[BlazingTrails]

Being a 2003 the first thing I would do is check the fuel pressure regulator. I am surprised it even starts and 32 psi......

 

[Midnyteryder196]

midnightfuel.JPG

I double checked the specs and there is nothing separate about the LWB. This is part of the fuel system diagnosis page where the pressure is between more then 0 and less then 57. I've never had one of these with fuel pressure between those values, it's been either good or none. My first thought is to try another gauge before doing anything.

Alright I will see if I can get it into a shop to see if they can check the pressure.

Its had the p0171 for almost a year now. And hard starting while warm for about the same amount of time. Just in the last week its been hard starting while warm more frequently. To the point where you have to let it sit for half an hour to an hour before it will start back up.

List of parts replaced in the last year. Not all are related to this issue but other codes too..

Intake bolts checked for tightness
Checked over vacuum lines
Fuel filter
Fuel pressure regulator
Upstream 02 sensor
Evap purge solenoid or actuator. (One up by motor)
Fuel cap
Intake air temp sensor
Cam sensor
Cam position actuator
Thermostat
Temp sending unit

Edit:
when it won't start right up after it's been running and then shut down for 10-20 min. You have to pump the gas just as it is just about to fire to get it to start. If you do that it will usually fire right up.