Testing fuel system / replacing fuel pressure regulator

[phychotron]

To answer my own question for anyone else who might have the same problem:

Yes, it was the fuel pump. It hummed for a second or two when I jumped the connector, I pulled the jumper and fired right up after that.

I wanted to note though that I should have tested for power at the pumps 2 prong plug just above the drive shaft before i dropped the tank. If it wasnt the pump it would have been all in vain.


Tank looked fine. A mechanic I talked to said if the outside looks fine the inside is usually fine...but there are some tank restore systems that work. I just replaced the rotting hoses amd clamps. he suggested brake cleaner thru the hard lines but that would have been teedious.



Ospho suggested their product would have worked fine though...

[Ian R.]

Hi all!

I have been trying to track done an issue with my van. Nothing serious, but it is more of an annoyance. Basically it takes a few cranks and taps to gas peddle to get the van started while it is cold. But it starts up perfect once the engine is warm. The second issue ( maybe unrelated) is I can’t get the idle to be below 1000rpm. I have changed out the TPS (had to make a throttle body gasket from a universal gasket as they are no longer available, but that is a different story) with no luck. I have also tried to adjust the idle with the idle screw. But the idle seems to revert back to where was prior to adjusting the idle screw after a few minutes of driving.

So my theory is that the fuel pressure regulator is not functioning properly. Maybe letting to much fuel in with increased pressure creating a higher rpm idle. Secondly, when the engine is off the pressure then leaks in the line creating the starting issue.

A question I have for those that have changed a fuel pressure regulator is, have you replaced the two brass gaskets highlighted in the attached image? I have purchased them along with a new union bolt (the one currently on the van is slightly stripped and I am afraid it will not be able to be reused), but the existence of the brass hackers are not described in the repair manual when replacing the fuel pressure regulator.

Thank you for your shared experience in advance!

if interested in part numbers

Union bolt part number: 90401-08004
Brass gasket part number: 90430-08011

attached is the parts diagram and image of the replacement parts I have

Ian

[Ian R.]

Sorry part of previous post

[Jan-Willem]

Hi Ian, I am sure you already have checked it, but a longer start, when cold, and a high idle, are both also symptoms of a bad battery. If the voltage when cranking drops too low, it is harder to start. Then the alternator makes then engine idle up, to charge the battery.

[Ian R.]

Thank you for the tip! I’ll check the battery before I replace the FPR.

[MarkH]

... it takes a few cranks and taps to gas peddle to get the van started while it is cold. But it starts up perfect once the engine is warm. The second issue ( maybe unrelated) is I can’t get the idle to be below 1000rpm. ...

I would check the fuel pressure with a gauge to rule out fuel pressure issues before replacing components that might not be the issue. Your symptoms sound like a vacuum leak to me. It's a quick check make sure all the vacuum hoses are attached and not cracked or degraded. A vacuum leak could also be caused by leaking intake manifold gaskets, leaking rubber grommets around the nuts holding down the valve cover, valve cover gasket, oil dipstick seal, pcv valve grommet, etc. I've never tried it, but many people use a flammable spray like carb cleaner/throttle body cleaner. You spray around those components when the engine is running at idle. If the idle speed changes when you are spraying at a particular component, it's because the spray was sucked into the component meaning it is leaking. I'd be semi-afraid of causing a fireball using this technique, but it seems to be pretty common and most people claim to have survived.

[Metalghost]

Looks like this might be the right place for my issue. I have similar issues to another user where the 86 Van starts but dies immediately. I measured my pressure for the PR and it is a little high. 42 for a range that is spaced 33-38psi.

1) is 4psi over enough to cause trouble. I saw an earlier answer was the van can compensate some with the O2 sensor. But not sure when is too much. 50psi was deemed not working from the authors post.

2) I’m in process of changing all vacuum lines off the throttle body. I read that vacuum leaks can cause idle problems of start/running problems. I check spark and saw spark in all 4 but thinking of going through the distributor for timing and rotor/cap condition next.

3) Could a bad mass air flow sensor be throwing off the mix after it turns over?

Open to any help. Trying my best to be smart and diagnose over throwing new parts at the problem.

[timsrv]

Having a little too much fuel pressure will not cause your problem. I have full gauge sets in my vans (including fuel pressure) and my 86 van had high pressure like that for years before I replaced the FPR. You are correct about the system compensating. The ECU adjusts injector fire times based on info it gets from the o2 sensor, so if there were too much fuel pressure it would be compensated for. So even though the FPR is not within it's specified range, it's not the cause of your issue.

There are other threads that should be able to help you diagnose. Search for "coil" "igniter" (maybe some results in "ignitor") and "Electronic Control Unit" Having some extra parts around is a good thing, so if you can find any of these things cheap in a salvage yard or maybe eBay, they can save lots of troubleshooting time and heartache. Good luck! Tim

[MarkH]

Looks like this might be the right place for my issue. I have similar issues to another user where the 86 Van starts but dies immediately. I measured my pressure for the PR and it is a little high. 42 for a range that is spaced 33-38psi.

1) is 4psi over enough to cause trouble. I saw an earlier answer was the van can compensate some with the O2 sensor. But not sure when is too much. 50psi was deemed not working from the authors post.

3) Could a bad mass air flow sensor be throwing off the mix after it turns over?

I think if the signal from the O2 sensor goes out of range (too high or too low), it should generate a fault code. Same with the MAF sensor. Assuming your check engine light isn't burnt out, are you getting any codes? There is a connector in the engine bay to jumper to check this.

[MarkH]

Also, there is that flapper-type valve in the air intake that makes a switch to run the fuel pump. If that switch is faulty or the valve is not opening properly, the fuel pump will shut down. When you tested the fuel pressure was it with the fuel pump test connector jumpered?

[Metalghost]

Wow. This is good info.

Yep I jumpered the pump to test it. Also I don't see any fault codes on the engine light. That does work as I see the bulb on when I turn on the car. I saw how to get into that code reading. I can check again but didn't see any errors popping up. But if there is a way to check the O2 and MAF sensor I will do that.

I'm replacing all vacuum tubing and the big Tbody/cleaner hose to make sure I don't have a leak. After "air" is all sorted I'll try poking around the spark side more. Already check there is a spark but can dive into the distributor/ignitor/wire.

Open to anything else or redirects to articles. Been through the search for ignitors and coils already.

[Ian R.]

Closing out my question about the part numbers. Yes these fit the FPR (the ones originally on the van were washers without the tabs).

This is a tedious task. I recommend unbolting the heater hoses nearby, wrapping a rope or shop towel around them, and pull them out of the way (tie them off when retracted). I was able to sneak a 3/8 drive socket on the shortest extension to remove the union bolt.

Also use a Phillips head on the two FBR mounting bolts to get the started. It took a few tries to have them threaded properly. Once they are threaded use a socket and long extension to get them snug and followup with a torque wrench 5.9 Nm for the two mounting bolts and 20Nm for the union bolt.

[armorrell]

Tim, I can't thank you enough for posts like these. So much generosity sharing the knowledge and helping out with the hard work of making it all available.

So, I have several items to ask about/mention....
#1- Is there any difference between the 2WD and 4WD Fuel Pressure regulators?
#2- Is there a typical expected lifespan? Should it be changed at a particular mileage as a maintenance procedure?
#3- Reason I find myself on this thread: I've noticed over the past couple of years a gradual decrease in engine power.
With that in mind I've: {A} updated the Cat, (needed it). {B,C} Done a full tune up, New fuel filter (both due). {D} New O2 sensor... (Note: in refreshing the O2 sensor, I realized the previous owner deleted the downstream sensor and I've been running the van for the past 20 years without it, pretty crazy to just now realize it) {E} Vacuum lines have all been upgraded to silicone {F} New high performance air filter. {G} new PCV Valve. {H} new fuel pump in 2020.
#4- With all that, nothing has changed power-wise. So I'm wondering if it could be a slowly failing FPR, Dirty injectors, after market throttle position sensor, etc?

Any thoughts on which mineshaft I should descend into first? ;) I'm going to start doing some proper testing as soon as it warms up a bit.

Bonus: I might've found a resource from the UAE that has the TOYOTA OEM FPR available. regulator-assy-2328073040 I have started an order and we'll see if they have it available and how much it costs to ship. I'll update as I get a response from them.

[Ian R.]

Hi Armorell,

With regards to loss of power the Service manual (can be found and download for a thread on this site) has pretty good trouble shoot on the subject. Did the tune up include rotor, cap, potentially a coil, check the timing? There is nothing in the service manual on testing the igniter, just to replace it if it is suspected. Since the loss of power has been gradual it probably could not be brake drag. Any unusual front tire wear? Could be needing front alignment. How many miles on the van? Has there been a gradual decline in fuel efficiency? Have you checked compression?

i recently replaced the FPR and did not notice a change in power, but I don’t know if my van is suffering from that issue.

Something that I have noticed in my life is that we all lose power with age and mileage

[timsrv]

Tim, I can't thank you enough for posts like these. So much generosity sharing the knowledge and helping out with the hard work of making it all available.

So, I have several items to ask about/mention....
#1- Is there any difference between the 2WD and 4WD Fuel Pressure regulators?
#2- Is there a typical expected lifespan? Should it be changed at a particular mileage as a maintenance procedure?
#3- Reason I find myself on this thread: I've noticed over the past couple of years a gradual decrease in engine power.
With that in mind I've: {A} updated the Cat, (needed it). {B,C} Done a full tune up, New fuel filter (both due). {D} New O2 sensor... (Note: in refreshing the O2 sensor, I realized the previous owner deleted the downstream sensor and I've been running the van for the past 20 years without it, pretty crazy to just now realize it) {E} Vacuum lines have all been upgraded to silicone {F} New high performance air filter. {G} new PCV Valve. {H} new fuel pump in 2020.
#4- With all that, nothing has changed power-wise. So I'm wondering if it could be a slowly failing FPR, Dirty injectors, after market throttle position sensor, etc?

Any thoughts on which mineshaft I should descend into first? ;) I'm going to start doing some proper testing as soon as it warms up a bit.

Bonus: I might've found a resource from the UAE that has the TOYOTA OEM FPR available. regulator-assy-2328073040 I have started an order and we'll see if they have it available and how much it costs to ship. I'll update as I get a response from them.

#1 Same thing on both. All years of van have interchangeable regulators, but Toyota slightly raised pressure on the 88 - 89 regulators though (good thing).

#2 There is no "expiration date" on these but there are 4 common failures of the regulator: failure to reduce fuel pressure to the correct value, internal leakage, external leakage, tearing/breakage of the internal vacuum diaphragm. None of these failures should cause a reduction in power, although external leakage could be dangerous. Internal leakage allows fuel to return to tank, and that will delay engine start-up (long cranking time). If it leaks or if you experience long cranking times, that is a good reason to replace. The other type failures will probably not be noticed unless you observe using a fuel pressure gauge. It's been my experience that OEM regulators fail in one way or another @ ~ 150k miles. I haven't had very good luck with the aftermarket ones.

#3 I didn't see spark plugs or plug wires on that list....these can cause a gradual power issue.

#4 Regarding TPS, I've only used Toyota and Bech Arnley. Both have served me well. Are you getting any codes? Dirty injectors are a possibility, but in my experience, they either work or they don't. Do you have a miss? I've had several issues with injectors that were completely clogged (no fire in that cylinder), but that was caused by a contaminated fuel system. When I've experienced complete clogs it's always been #3 injector.


Good luck with the OE regulator order. Please let us know if you are successful. IMO that is too good to be true and will not likely pan out. These regulators are NLA through Toyota now but you can still find them on eBay (search using the Denso number). I looked at one listing and it looked a little iffy in the pics (almost like it had been used), yet they wanted $156 for it. I stocked up on these a while back (before they went extinct).......and no, I'm not selling them (sorry).

[armorrell]

Thanks for the response Ian R.

Did the tune up include rotor, cap, potentially a coil, check the timing? Yep, switched out the Coil (It had died recently). New plugs, Plug cables, cap and rotor. Haven't checked the timing though.
Any unusual front tire wear? I do have the front passenger wheel creating some black brake dust. Although there isn't any noticeable wear on the rotor or the pads... or any noise for that matter.
Could be needing front alignment. Doesn't pull at all, but might still be worth checking out.
How many miles on the van? 240,000 Miles
Has there been a gradual decline in fuel efficiency? My fuel efficiency averaging 16.7 MPG. Kinda feel like it should be better.
Have you checked compression? I did check compression, but need to redo it. I missed a step and don't trust my reading was complete. So that'll happen again soon.

Something that I have noticed in my life is that we all lose power with age and mileage[/QUOTE] Totally

[armorrell]

Excellent thanks for the feedback.

"I haven't had very good luck with the aftermarket ones."
I found another one that's supposed to match. Made by a company named Standard- Link is here: https://www.ebay.com/itm/32525853593...mis&media=COPY

"Good luck with the OE regulator order. Please let us know if you are successful.
Unfortunately they got back to me and said they have no stocks. :(

"These regulators are NLA through Toyota now but you can still find them on eBay (search using the Denso number)"
I couldn't find the complete Denso number in the previous posts. Just the link to the eBay page, which has since expired.

"I didn't see spark plugs or plug wires on that list....these can cause a gradual power issue."
Yep changed out fresh plugs, Plug cables, cap and rotor.

"Regarding TPS, I've only used Toyota and Bech Arnley. Both have served me well. Are you getting any codes?"
Only code thus far was an oxygen sensor code while climbing a mountain a while back. New O2 sensor and it hasn't shown up again since.

"Dirty injectors are a possibility, but in my experience, they either work or they don't. Do you have a miss? I've had several issues with injectors that were completely clogged (no fire in that cylinder), but that was caused by a contaminated fuel system. When I've experienced complete clogs it's always been #3 injector."
I do have a very minor miss sometimes when I start cold, but it goes away very quickly and then doesn't show again for a good while. Very intermittent. Makes me think I need to check those injectors as well.

"I stocked up on these a while back (before they went extinct).......and no, I'm not selling them (sorry)."
As you should, stock up I mean. That's what I intend if I ever find some OE ones. ;)

Thanks again for the help. And If I figure out this power loss thing I'll try to remember and update here.

[timsrv]

I just wanted to clarify, when you say you got a code, was it one that just popped up for a minute while driving or did you put a jumper in your Check Engine Connector to capture?

The Denso number 2328073040 is in that link you provided (in the title). I used a Standard regulator before and although it performed okay It leaked externally so I took it off and replaced with Denso. The threads for the banjo bolt were not square with the sealing surface so the crush washer could not quite seal. I probably could have doubled up the crush washers, but was disgusted with the obvious quality issue so I trashed it. Still, I probably got the one in a thousand with that problem so I'm guessing yours will be fine. FYI, I still use the Standard "Fuel Pulsation Dampers", but the threads are always trashy and require chasing with a die before installation. Tim