1998 V70 T5; problem hot starting & occasional brief power loss at speed

clifford06 · Post by **clifford06** » 28 Aug 2019, 15:16

I have been suffering from the same type of " no start when hot " problem . Would a bad engine coolant temp sensor cause this problem ?

Post by **abscate** » 28 Aug 2019, 20:17

It can. You can find the ohm chart to test it buried in this forum. I think I have it referenced in my 1999 maintenance thread

clifford06 · Post by **clifford06** » 30 Aug 2019, 16:31

Thanks. I found a test procedure on Pelican Parts . Sensor should read 3.5 ohms. DME is 5 volts and .1 volts at 60 F. I couldn't get an accurate reading due to my lack of meter reading experience. But from the look of the sensor ( leakage, wire heat damage ) , I'm going to replace it with Volvo sensor. I remember changing it a few years ago with a aftermarket brand.

Post by **abscate** » 30 Aug 2019, 19:46

That’s not the right resistance. It’s between 500-5000 ohms working range.

I’ll hunt it down

viewtopic.php?f=1&t=79330&p=427389&hili ... ce#p427389

clifford06 · Post by **clifford06** » 04 Sep 2019, 07:34

I put in a new ECT ,and still get a no start after a drive to get it up to operating temperature. Jumping the fuel pump relay does not get it going. Bad fuel pump ? If so I'll just get a replacement to buy some time. Thoughts and opinions are welcomed. This car is getting on my last nerve .

Post by **abscate** » 04 Sep 2019, 08:43

You really need to measure the fuel pressure. That will tell you if the pump is marginal, rather than guessing at what part is bad. There are a lot of things in a fuel delivery system, all interconnected, so guessing is expensive.

Fixing by symptom - "My car does this, what part to replace?" Quick to 'fix' then lost time rinsing and repeating.

Fixing by diagnostic - "My car does this, what sub-system do I troubleshoot? Just like the pros do.

If you want to really see the process of a guy who gets this, read shockwaves saga on his fuel pump on his XC90. He actually diagnosed a poor workmanship dealer installed fuel pump by staying with the diagnostic path.

Post by **wizechatmgr** » 04 Sep 2019, 20:19

Just had 2.2k Ohms at ~70 F on my '99

evdrive · Post by **evdrive** » 09 Sep 2019, 05:35

Update: It was the Fuel Pump Relay!
So I checked and I had last replaced the relay with a crappy KAE one. I should have realized that right away. Volvo one is the way to go with that relay always!

Post by **abscate** » 09 Sep 2019, 07:13

evdrive wrote: ↑09 Sep 2019, 05:35 Update: It was the Fuel Pump Relay!
So I checked and I had last replaced the relay with a crappy KAE one. I should have realized that right away. Volvo one is the way to go with that relay always!

Jumping the fuel pump relay does not get it going. Bad fuel pump

You might not be out of the woods if jumping it didn't help, but its not rare to have more than one thing wrong on old cars

clifford06 · Post by **clifford06** » 09 Sep 2019, 19:28

I replaced my fuel pump today with one I found on Amazon . Install was simple. I'll give it a test run tomorrow ,and see how it goes. Only thing left to change is the relay.

1998 V70 T5; problem hot starting & occasional brief power loss at speed

Re: 1998 V70 T5; problem hot starting & occasional brief power loss at speed