92 Ranger fuel issue.

mattmattf14 · Sep 26, 2016

On a cold startup the truck takes a few tries to start. Crank it over for a few seconds then it stumbles. Repeat two or 3 times and it will start. If I spray some fuel into the intake it will start right away. I have 40 psi koeo at the rail. New fuel filter, and also fpr. Needing some help. Once the engine is warm the truck will restart with no issues.

RonD · Sep 26, 2016

Test fuel pressure after truck sits overnight or 6 hours

Or try this test after engine sits over night
Turn key on and count to 3, turn key off
Repeat this 2 more times
Then try to start engine

If it starts right up then you are losing fuel pressure over time.
The 40psi pressure should be no lower than 25psi after engine sits over night, and it will stay 25 or higher for a few MONTHS, not hours, days or weeks.......months

For safety reasons the fuel pump only runs for 2 seconds when key is turned on, that adds about 10psi of pressure.
Fuel pump won't run again until engine RPMs are above 400, so after it starts.
Turning key on and off 3 times would restore at least 30psi of fuel pressure to the system, if it had dropped to 0psi.

Also after engine is warmed up and idling, 700rpms, unplug the IAC Valve, RPMs should drop to 500 or engine may even stall either is good, no vacuum leak and IAC valve is working.

Long shot issue could be ECT(engine coolant temp) sensor, this tells computer when to run engine in "Choke mode", cold engines need extra fuel and higher idle to run.
Is the idle above 1,100rpm when started cold?
And then drops to about 700 after it is warmed up?

If so then ECT sensor is most likely fine.

mattmattf14 · Sep 26, 2016

Ect is good, tested. Iac is new and when unplugged idle does drop. Cycling the key multiple times doesn't affect the truck when starting.

RonD · Sep 26, 2016

Then I would try this test.

After engine sits over night
Unplug both coil Packs, the 3 wire connectors, so you want a no start
Crank engine over 2 times and count to 5 each time
Now pull 1 or 2 spark plugs, from different cylinders
The tips should be wet with fuel, if not fuel injectors are not opening.

In 1992, 2.3l the spark is done by the ICM module on front side of intake manifold.
It is connected to the Crank position(CKP) sensor and the Coil packs.
It doesn't "need" the computer to time and fire spark plugs.
The ICM sends the CKP sensor timing TO the computer, so computer can start and time the fuel injectors with crank position.
If for some reason this timing signal was intermittent, computer may not start injectors right away.
But I would think this would also cause CEL(check engine light) and set a code about no PIP signal

mattmattf14 · Sep 27, 2016

The injectors are opening. Tried that test and the plugs were wet. Also pulled the rail and activated each injector and getting a consistent spray among them all.

RonD · Sep 27, 2016

What fuel are you spraying into intake to get the faster starting?
Quick start is ether, which has a much lower flash point than gasoline at colder temps.

If plugs were wet then gasoline is flowing in on first crank.
If there is a no start then that only leaves one thing, with 2 possible causes
Gasoline is not heating up enough to be ignited by a spark, or spark is not hot enough to ignite cooler gasoline mix.

Compression heats up the gasoline so a spark can ignite it
Spark plug gap and coil decides spark plug heat

Ether ignites by spark at much lower temps, air or spark temps

mattmattf14 · Sep 27, 2016

I used carb cleaner. The truck will start without it but takes a couple cranking cycles before it will start.

RonD · Sep 27, 2016

Well then that is odd, gasoline auto-ignites around 500degF
Carb cleaner is close to 700degF
Ether is 320degF

So carb cleaner shouldn't help start an engine better if compression or spark heat was the problem, ether would.

So I guess you are back to a fuel issue.
Carb cleaner working means spark is there at first crank, and compression.

You could try pulling off the PCV or power brake hose from the intake before starting.
If fuel mix was too Rich then engine would be slow to start, in that case a larger vacuum leak would make it start easier

tomw · Sep 28, 2016

Put a gauge on the fuel rail when cold. Attempt to start. Betchu you do not have pressure until after 3-4 crank cycles, and once pressure develops, it starts.
I think the only thing changing after a few cycles is that the pump has had time to run for a few seconds at each attempt. Nothing else changes except the clock.

tom

mattmattf14 · Sep 28, 2016

Just tried it again. I have 40 psi koeo. While cranking the gauge continues to read 40 psi. Once idling it reads about 32 psi. Also while idling I revved the truck up to about 2400 rpm for a second and when the truck came back down to idle it stalled out.

tomw · Sep 29, 2016

I have not gone back & read... Have you checked/cleaned/replaced the IAC? It is in charge of keeping the engine running at the proper rpm, from cold idle to hot idle, and when the A/C & PS loads come & go.
I have an old truck that will start, run at fast idle, and want to stall the moment I give it gas. I figure one of three things that pop to mind. IAC is sticky, and doesn't respond quickly to 'taking over' when you goose the gas, and then let off. The CTS or ACT - coolant or incoming air temperature sensors - are reporting 'warmer than actual' temperatures, so the computer is not considering you need a richer mix for a cold engine/cold air condition. May be one of those three things. Measure the CTS and ACT ohms and refer to the temperature/ohms table to determine compliance. Remove clean and replace the IAC, with the battery disconnnected, re-connect battery and let the system re-learn the IAC response & engine condition. MAP sensor may be off, also, as it informs of engine load based on manifold vacuum. Or you have a MAF, which reports air coming in, and may mis-report if dirty.
tom

mattmattf14 · Sep 30, 2016

I already replaced the IAC. Tested the ACT and ECT. Cleaned MAF. Just drove the truck, it wants to stall out when cold but when it warms up it runs perfect.

tomw · Sep 30, 2016

I think a reading of 40 psi w/o regulator is a bit low. Seems to me it should be above 45 psi. The newer returnless fuel injector systems are higher yet.
Have you checked delivery volume? Measured fuel over measured time? It may just be a sort-of weak pump that has enough to work when hot, and the demand lower, but when cold just doesn't supply enough to run properly.
Some pressure gauges have a relief valve with diverter function so you can capture a flow of fuel coming from the pump. I'd check volume over time.
tom

mattmattf14 · Oct 1, 2016

I only had a gallon container laying around and I got less than 1/4 of it from the return line at 30 seconds.

RonD · Oct 1, 2016

ECT sensor data initiates the Computer's Choke Routine for the engine, poor running Cold engine usually means Choke is not working like it should.

Cold start should have high idle, 1,000+ RPM, started by ECT data and computers Choke Routine
Then idle should slowly drop to 650-750 warm idle RPMs over the next 5 to 10 minutes as engine coolant warms up.
If you are not getting high RPMs on cold start, then computer is not running the Choke Routine, so either ECT or wiring is bad or Computer is

Lack of fuel pressure would mean poor running cold or warm, especially at highway speed, higher fuel demand

92 Ranger fuel issue.

New Member

Official TRS AI

New Member

Official TRS AI

New Member

Official TRS AI

New Member

Official TRS AI

Well-Known Member

New Member

Well-Known Member

New Member

Well-Known Member

New Member

Official TRS AI

Sponsored Ad

Sponsored Ad

Today's birthdays

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals