Fatty acyl-coenzyme A (CoA) diphosphatase that hydrolyzes fatty acyl-CoA to yield acyl-4'-phosphopantetheine and adenosine 3',5'-bisphosphate (By similarity). Preferentially hydrolyzes unsaturated long-chain acyl-CoA substrates such as oleoyl-CoA/(9Z)-octadecenoyl-CoA and arachidonoyl-CoA/(5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA in the endoplasmic reticulum (ER) lumen (By similarity). This catalytic activity is required for maintaining ER structure and for lipid droplets (LDs) biogenesis, which are lipid storage organelles involved in maintaining lipid and energy homeostasis (PubMed:18160536, PubMed:26504167) (By similarity). Directly binds to diacylglycerol (DAGs) and triacylglycerol, which is also important for LD biogenesis (PubMed:22106267) (By similarity). May support directional budding of nacent LDs from the ER into the cytosol by reducing DAG levels at sites of LD formation (By similarity). Plays a role in the regulation of cell morphology and cytoskeletal organization (By similarity). an acyl-CoA + H2O = adenosine 3',5'-bisphosphate + an acyl-4'-phosphopantetheine + 2 H(+) (9Z)-octadecenoyl-CoA + H2O = adenosine 3',5'-bisphosphate + 2 H(+) + S-(9Z-octadecenoyl)-4'-phosphopantetheine (5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA + H2O = adenosine 3',5'-bisphosphate + 2 H(+) + S-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-4'-phosphopantetheine H2O + hexadecanoyl-CoA = adenosine 3',5'-bisphosphate + 2 H(+) + S-hexadecanoyl-4'-phosphopantetheine Widely expressed, with highest levels in white and brown adipose tissues (at protein level). In the heart, mRNA expression levels do not correlate well with protein levels, suggesting post-transcriptional regulation in this organ. Homozygous knockout mice display embryonic lethality (PubMed:30923760). Heterozygous knockout mice exhibit shortened left ventricular end-diastolic dimension and shortened left ventricular end-systolic dimension (PubMed:30923760). They also exhibit improved profiles upon pressure overload-induced heart failure (PubMed:30923760). Belongs to the FIT family.