Please Help Diagnose Hard Starting Fuel Pump Relay – Check Valve problem.

[Daniel ODonnell]

2005 Toyota Sienna
Car is hard to start after sitting overnight. Once started it runs fine – does not hesitate at all.
The starting is getting gradually worse each day – today it took 20 cranks to start
When I turn the key to on (but not crank) I do not hear the fuel pump hum – that makes me think the relay or supporting fuses are bad – I swapped with Horn relay and no difference.

My key symptom that I cant figure out is the fact that has gotten gradually worse over 2 months. From 2 extra cranks to fire up to now 20 cranks.

Could it just be the filter?
Once again it runs fine once started and startup all day long and run fine all day long. Just a problem after sitting overnight.

Lead me to think check valve problem,, but why would that get gradually worse?

Any help on what I can rule out and best course of action?

Thanks

Topic

[Richard Kirshy]

The fact that you can eventually get the engine to start says that at least the electrical portion is functional.
Not knowing how the vehicle has been maintained over the years.
My first thought would be to check the fuel pressure with a gauge on a cold start.
Find the spec for your specific vehicle and engine and see if they are a close match.
From there if you don’t know how long its been since the last fuel filter change, might invest the few $$$ and toss a fresh one in either way.

If it is a faulty check valve..
Try cycling the key from off to on (with out cranking the engine) several times to pressurize the fuel system and see if that improves the crank time.
If it does, your looking at a replacement fuel pump.

One other item that might be a cause is the fuel pressure regulator.

[Daniel ODonnell]

Thanks Very Much for your reply.

Of all of my symptoms, the one that is most telling to me is the fact that this has gotten gradually worse over time. Over 6 weeks, going from 3 cranks to start to now 20 cranks. With the fact that it has been so gradually worsening, would that make you lean toward, Fuel pump and check valve, regulator or filter. Once again after started in the morning it runs and starts fine all day as long as it doesn’t sit for more than 6 hours.
Thanks Again!

[Richard Kirshy]

Could be anyone or more of those items …
I do not like to guess at a problem.
Better to invest a little time in diagnosing the problem to pin point the issue(s) and save the cost in time and money firing the parts cannon at it.
None of the testing I suggested should take much time to do and it will yield you a better direction to follow.
If you are uncertain as to how to do them, there are videos on youtube showing each procedure.

[Its me]

Before I would throw parts at it, I would get a fuel pressure test done on it. Toyotas are known for fairly robust fuel pumps, so I don’t always lean that way (unlike GM fuel pumps).

FWIW The fuel filter is located in the fuel pump and I have never seen a Toyota pressure regulator on these model years be an issue.

An issue with a Crank position sensor signal can cause starting issues as well (will not turn on the fuel pump)

As always make sure your battery connections are CLEAN and TIGHT! – Have seen this as a no start/hard start issue…

Good luck

-Karl

[Daniel ODonnell]

Hadit checked by mechanic. He says that fuel delivery system and pressure is good. He suggested a Fuel Treatment. That seems like a shot in the dark?

[Its me]

I would say a fuel treatment is a shot in the dark. If it is an In tank one, the only one that remotely works is Techron. The rest is snake oil. As for injection cleaning, I have my doubts.

Since the fuel delivery system and pressure is good, I would start looking elsewhere for your issue. Ensure you are getting spark and ensure you have a good battery.

Good luck

-Karl

[Author]

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